Author Topic: Bending Mahogany
PeterC
posted 05-07-2000 10:44 PM
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Given the interest in bending white oak in another string, I thought you all might be able to help me with the question of bending 1/2" mahogany plank for my 18' Ed Monk runabout. The plans suggest that the garboard strake and 1 ot 2 others will need to be steam bent for'd. My planking stock is about 30 years old and well-dry to say the least. Do I soak it before steaming or will the cell walls have "set". I cannot get other than kiln dried mahogany new here in New Zealand.
I would appreciate the group's advice, especially as I have few wide planks and hope to avoid split or broken strakes.

Thanks

PeterC


lee
posted 05-07-2000 11:06 PM
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soaking would not hurt. I have used dish soap to help break surface tension. I dont know if it really helps but your planks are clean.

Don Danenberg
posted 05-08-2000 02:18 AM
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Peter, I plank 6-10 boats per year with 1/2" Mahogany that is kiln-dried (10-12%MC). Soak the cut plank blanks for 2-3 days to get the surface saturated. This acts as a conductor to transmit the heat to the interior.
The important point is to clamp carefully, especially at the stem. Use scrap 1"x4"x1/2" plankstock beneath each clamp to distribute the forces rather than focus them. This will also help keep the clamps from compressing the soft Mahogany surface. Allow to dry for a week before fitting them to avoid shrinkage. Don

PeterC
posted 05-08-2000 06:14 PM
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Thanks Guys. Don, two quick questions. Do you see any problems with the really old Mahogany? And forgive my ignorance, but do you mean I should leave the plank clamped for a week before fastening? And does this mean I can only put one plank on a week before I can spile for the next?
****, that's three questions!
PeterC

Don Danenberg
posted 05-08-2000 07:59 PM
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G'Day Peter, I see no problems at all with the really old Mahogany, in fact it may very well be of a higher MC than when it came out of the kiln. Making it easier to bend. Here in Michigan, it would reach a moisture equilibrium of ~18% in a couple years. Check it. I was covering my *ss when I said one week. If you have to soak the wood, it will expand. A six-inch Mahogany plank can expand 1/8" with soaking and thats the gap you'd end up with if you fit it right away.
I bend all planks (usually only top two at sheer forward - top two aft if barrelback tumblehome) on same day and let them dry, clamped in place, while I begin planking the boat from the chine up. At one day per strake all the way around, you've got 3 or 4 days drying time before you get to them. I do not spile exact sizes till after steaming and drying. Do you use the foolproof router method for perfect plank fitting? Don

PeterC
posted 05-08-2000 09:47 PM
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Don
NOW you've got me intrigued! I haven't ever used the word "foolproof" or "perfect" when it came to me and my boatbuilding skills (first boat you know), which is exactly why I built a 1/4 scale model, so I could discover the MYRIAD of things I could (and did) do wrong. And I guess I've seen about 1% of all possible disasters. I'm just learning as fast as I can. FOOLPROOF? Tell me more, please.
PeterC


Dave Greenup
posted 05-08-2000 10:24 PM
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I'm intrigued to Don tell us more.
Dave Greenup


Don Danenberg
posted 05-08-2000 11:36 PM
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AAAARRRGGGGGHHHHH!!!!
I just typed a nice compact description of the procedure and was almost done when the stupid ISP dropped offline. Its too late to re-type. I'll try to paste an article I wrote for Classic Boating mag #88-March, 99.
If this doesn't work call 1-262-567-4800 and get issue #88 (its better with photos anyway)
Don
Whoops, wrong computer, I'll send tomorrow from shop.


Don Danenberg
posted 05-09-2000 01:51 PM
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G'day Peter, the following is an article from last year on the router planking technique.
12-24-98

CLASSIC BOATING # 88 MAR/APR 1999

NEW HULL PLANKING WITH THE ROUTER METHOD
By Don Danenberg

The router method of fitting new planks is an ingenious blend of new technology with old material procedure. This one innovation alone makes planking a hull with new wood easier and quicker than replanking with original planks and leaves one with a far more sound and valuable hull.
I first read of this approach to planking many years ago in articles in both Classic Boating and WoodenBoat magazines and was impressed immediately by not only the time savings this would allow, but by the automatic accuracy it created. One no longer needed years of experience in the tedious process of trial fitting planks with a handplane.

The basic concept of the procedure is that a fence attached to the router base rides along the top edge of the chine or previously installed plank and trims the bottom of the next plank to an exact fit. An added benefit is that the base of the router follows the contour of the hull surface, automatically directing the router bit to also cut the correct bevel to the plank edge for a dead tight fit, plank to plank.

The best router for this procedure is a small machine called a “laminate trimmer” that has adequate power for the job and will more easily fit around the many clamps needed for the job. My favorite is the Bosch 1608.
The best router bit to use is a solid carbide 1/4” x 1” “up spiral” bit. Straight bits may be cheaper, but are far more likely to splinter changing grain. The up spiral design also removes the wood chips from the cutting area.
You will have to fabricate a new base for the router as shown in the photo and diagram. You will also have to prepare a half-dozen or so 1” x 4” x 5/16” spacers.

Continuation with this procedure assumes that you have already completed all frame, plank batten and deckbeam repairs and have thoroughly secured the hull in a position that is plumb and level. The hull should be blocked up high enough so that you will be operating the router in a comfortable position in front of you. The first few strakes are easiest to approach from a height-adjustable shop stool on wheels. Temporary bracing from the chine to floor will help hold the hull in shape while you are working on it. Take diagonal measurements of the transom to insure it is square with the world. Half-breadth measurements, outboard from a taught centerline with plumb-bobs to the keel, should be taken at every frame station.
The hull should be square, plumb and level and all frames, including deckbeams and plank battens, should be properly sealed, bedded and re-fastened before the topsides' planks are installed. Once these planks are tightly secured, they will hold whatever shape the hull frames were in; straight or not, this is up to you.

Make sure that your work area allows for planking both sides of the hull at the same time. If you attempt to plank the hull one complete side at a time, the weight of the planks as well as the tension created by thousands of fasteners will pull the topsides out of shape.
This will cause the boat to always want to pull to one side when underway and look noticeably crooked at the stem or stern. A serious buyer would consider such a hull no more valuable than a “gray boat."
It is best to install the planks one “strake” at a time, from one side to the other. A plank strake is any number of planks in a line from stem to stern (usually two planks, a forward and a follower, in hulls under 22 feet).

I prepare the new plankstock with careful attention to grain configuration, color, etc. Hopefully, you will have obtained enough matching plankstock in adequate lengths to match the original plank butt schedule. The most cost effective means of obtaining 1/2” Mahogany plankstock is to order 6/4 lumber and have it re-sawn and surface planed to two ‘book-matched’ 1/2” planks. I might plank as many as ten boats a year and still find it less expensive to order wood from the supplier already re-sawn and surfaced, than to waste my time on these procedures.
The best procedure for ordering wood for the total re-planking of a gray boat would be as follows:
Determine how many board feet you will need for the project ( for example, a 1950
Chris Craft 17 foot Deluxe requires about 350 bd/ft of 6/4 resawn to 1/2” plankstock to completely replace bottom, topsides, deck and ceiling planks.)
When you receive your lumber first select the most beautiful pairs of plankstock to complete the deck, transom and ceiling planks. This is 90 percent of the wood you will see at a boat show with the boat in the water. Mark this wood and set it aside for later.
The next group of planks to be selected for color and grain, etc. will be for the topsides.
The least beautiful and poorly matched planking can be used for the bottom, under paint.

If you are using original planks as your patterns, do not simply trace them onto the new plankstock until you have trial fit them into their original positions. After you have straightened out years of sag or hog in the framework and have refastened this structure into a straight, plumb and level condition, you will most likely find that the original planks will still exhibit the hogged shape they have come to know. As you are planking the hull from the chine up, trial fit each original plank in it’s original position to see if the shape is correct enough to trace. If the shape is no longer correct; use it as a spiling batten and spile the correct shape from it.

After you have assured the correct shape you may spile or trace onto selected pairs of resawn plankstock. Make sure the book-matched pairs are properly aligned as to grain and keep them clamped together well and you can cut them out two at a time. Stay at least six inches or so away from the ends of your plankstock to avoid weaknesses and cracks created during the kiln drying process and inspect all surfaces along the full length for such problem areas as reaction or compression wood or windbreaks, etc. ( See Classic Boating # 82- Lumber).

I have changed my router procedure in ways that I believe allow for quicker construction, more accurate plank lines and built in error control. One must, however, remain methodical throughout the procedure.

I cut out the pairs of plank blanks with a Bosch 1587 jig saw with hollow ground blades.
There are reasons this particular tool has won multiple industry awards. I have witnessed this jig-saw’s ability to turn ham-fisted amateurs into proficient craftsmen. The only added direction I have had to give apprentices is to direct steering from the back of the tool as opposed to steering it from the blade at the front. Experiment with this tool on long straight or curving lines on scrap pieces of plankstock. Steering the tool 1/8” at the back of the tool means only about 1/64” change at the blade mounted six inches forward at the front end of the tool. Set it’s orbital action for ‘0’ when cutting cross-grain so as not to tear up the plank edge. Set it’s orbital action for ‘3’ when ripping the length of the planks. The best blades, replaced often, will make the work proceed smoothly and accurately and save time and money in the long run. Changing the $ 2.00 blades every other strake of planks (four pairs) will not only cost about $ 6.00 overall, on the average 20 footer, but will make you think you are some kind of expert. Believe me here, the blades will not look burnt or feel anything but ‘sharp’ to the touch. There will, however be a decided difference in control.
The hand plane I use is a Stanley G12-060 (low angle). Angle the blades approach diagonally when cutting cross-grain, the shearing action makes end-grain easier to cut.
If nobody you know owns this quote; let’s pretend it’s mine:

“The right tool makes all the difference.”

When cutting out what I call the plank ‘blanks’, I begin with the chine strake forward pair. (Starboard-1-Forward and Port-1-Forward) Mark these indications on the proper surfaces with a pencil and include an arrow for up and for forward.

S1F & P1F

1) I first trim the hood end (the stem rabbet creates a protective “hood” for it’s forward end) or forward end and hand plane it to it’s exact intended line before I cut the top or bottom line. The excess wood at the top and bottom will help protect breaking short grain when hand planing across the grain. Remember to mark the plankstock cutoff so that it will be found later for bungs for that particular plank (S1F and P1F). In this manner you will have the best chance at perfectly matching bungs. Pile these inside the hull for now so they will not get lost.

2) Cut the after butt end of the forward plank (again, remember to mark the bungstock and put it away) and trim the butt joint with the hand plane so that you have a crisp, straight line without any backbevel.

3) Cut just outside the bottom line of the plank blanks leaving 1/16” of wood outside the line. This is the amount that you will hopefully be routing off during the procedure. DO NOT cut inside the line or that amount of wood will have to be routed off the entire length of the plank. If you have to, practice cutting lines on long lengths of scrap wood so as not to waste expensive plankstock.

4) Cut outside the top line by 1/2”. That’s right, 1/2” of excess wood to be trimmed later will allow for one or two mistakes in the routing procedure without destroying expensive grain matched planks. Mark a line on the jig-saw shoe that indicates this extra 1/2” and just follow that when you are cutting.

5) Verify that the chine rabbet is clean and unobstructed and clamp these two blanks onto the boat with at least one clamp per frame and set them up from the chine rabbet with the 5/16” spacers. Do not set the hood end tightly into the stem rabbet but in such a way that when dropped straight down, the hood end will be tight into the stem rabbet. The clamps may be placed directly onto the frames or placed between frames with the use of a scrap piece of wood that spaces the gap between the chine and the first plank batten. Learn the clearance you will need to have for the router to pass beneath the placement of the clamps.

S1A & P1A (Starboard-1-Aft and Port-1-Aft , first strake followers)

6) Cut off the forward butt end of the plank blanks but don’t bother to hand plane it at this time. It will have to be fit to the forward plank’s after-butt-end on the boat. (remember to mark and save the cutoffs for bungstock- S1A & P1A).

7) Cut off the after end of the plank pair but this time leave three inches extra length.
This will allow plenty of stock for final trimming of hood and butt ends for the entire strake. (mark and save bungstock, I should no longer be reminding you of this but you will forget somewhere along the line- I admit, I still do. It’s exasperating to think you could end up with one plank in a perfect hull whose bungs don’t match.)

8) Cut off the excess of the bottom line leaving 1/16” wood outside the line. Do it right this time. Pay attention. Change the blade, if necessary. Lock your wrist and steer from as far back as your elbow.

9) Cut outside the top line by 1/2”. This is another one that can be hard to remember. With employees I’ve had to teach them to write + 1/2 at the beginning and end of this line when spileing or tracing so they are reminded before they cut.

10) Make sure the chine rabbet is clean and unobstructed and clamp these followers onto the boat with the 5/16” spacers and the butt joint relatively tight. Final fitting of this butt joint must be done after the planks are routed and fit into their final position.
Check the full length of the strake to verify that the clamps are tight and that the planks will not move while you are working on them. Slide a ‘no-go’ 3/8” spacer down the length of the opening to make sure you have no gaps larger than 5/16”. If the planks need to be adjusted in place do so with a hammer and a block of wood to disperse the blow.

11) Route ! The entire area should be prepared first, I use air pressure to blow the chine rabbet clean of debris. Sweep the floor clean of debris that might foul the stool wheels. Make sure the router cord and/or extension cord is laid out such that it will not catch on something. Watch that you do not step on the cord. Any of these surprises could yank this running tool out of your control and into your lap. This is a potentially dangerous and tiring operation, take all safety precautions necessary. Wear eye and ear protection. A lightweight full face shield works well.
I keep a two foot wad of waxed paper in my pocket to occasionally dress the router base with to keep things running smoothly.
Start at the after end of the starboard side and work forward. (Almost all router bits are designed to cut left-to-right.) Keep two hands on the machine at all times and maintain pressure down in order to keep the bit from cutting it’s way up into the plank, it will constantly try to do this. If the bit does cut up into the wood, reset the plank and route it again. One reason for the extra 1/2” at the top of the plank.
As you proceed, listen for a high-pitched whine. Mahogany owes much of it’s beauty to a constantly changing grain direction that can make working with it difficult and exasperating. When you hear this high-pitched whine turn off the router and allow it to come to a complete stop before attempting to remove it from the work. The whine is generally caused by the vibration of a sliver of wood breaking against rising grain. Cut off this sliver and proceed with the router. If the sliver has broken off above the router’s cut line, you may have to reset the plank down and route the entire plank edge again. This is another reason for the extra 1/2” at the top of the plank. If this happens too often, replace the router bit.
When you come to the stem plank rabbet, the guide fence of the router will prevent you from routing the last few inches. Turn the machine off, wait for complete stop and remove the bit from the work. Set your dividers for 3/8” and mark this last few inches to be trimmed with a handplane after the plank is off of the boat.
On the port side of the boat you will still have to route left-to-right. This will mean having to insert the bit, at the stem, into the space while the machine is running. Hook one lip of the guide fence onto it’s running surface and make sure the base pad is flat against it’s running surface. With the machine running, slowly rotate the bit into the work. The beginning few inches at the stem will need to be marked with the dividers and hand planed later. This is one procedure you should practice well on scraps. If you goof it up, tap the plank down and do it again.

12) Remove the planks from one side of the hull and note the 1/16” lip left on the inner edge of the plank. It is better to have to deal with this now than ruin the router bit on a screw or nail in the batten. With the handplane, trim this excess off. If any of this excess remains, it will keep the plank from seating tightly into the rabbet. I trim this excess with the handplane at a 45 degree angle so as not to effect the angle of the routed surface. I usually leave a 1/16” chamfer at this inside edge. It’s okay, it will be filled with bedding compound. Remember to address the first few inches where the router could not cut near the stem.

13) Clamp the forward plank back onto the boat after using air pressure to blow the rabbet clean. Use the hand plane to make any final adjustments to the hood end of the plank so that it fits snugly into the stem rabbet. This time when clamping the plank on, adjust the clamps so that a 3/4” x 3/4” batten will slide beneath them. Use a hammer with a wooden block to tap the plank down or forward.
Clamp the follower plank in place and mark and adjust the forward butt end until no light can be seen through the joint. Try not to backbevel the planks at the butt joint. They should seat tightly together. The after edge of the follower plank should be protruding past the transom frame, ignore this for now.

14) When you are satisfied with the fit of the lower plank edge and the hood and butt joints, you may proceed with shaping the planks top edge. Set your dividers at 3/4” (half the width of the plank batten) and set the pencil 5/8” or so back in it’s holder and riding the divider point along the top of the plank batten, mark the center point of the plank batten on the face of the plank at each frame station. This is ostensibly where the top plank edge should be. I have, however, seen the factory installations of these battens terribly unfair. The fairing batten gives one an opportunity to clean this line up somewhat, as long as you stay somewhere near the center of the plank batten for fastening purposes.
Slide the 3/4” x 3/4” x 20 foot fairing batten through the clamps that are firmly holding the planks in place. Using another set of clamps, attach the fairing batten along the set of lines that you marked. Make sure the batten extends past the point of the stem so that the final position can be marked at the point of the stem to verify the same plank height on the other side of the hull. It will be difficult to fair this batten with 30 or so clamps in your view, but not impossible. Walk up and down this batten loosening every other clamp a quarter turn and re-tightening it just to see if the batten wants to spring up or down to fair itself. Look at the batten from near and far and from different angles. Squint at it until the clamps disappear and keep telling yourself how good you are at this. Is it a sweet line? Is it in keeping with the shape of the hull? Look for humps or hollows in the line. Is the line still close enough to the center of the batten for effective fastener placement?
When you have decided on the final placement of the batten, mark the line well with a pencil or pen. If your hull is longer than your batten, simply move it aft and complete the procedure. When the line is fully marked, remove the batten clamps and fairing batten only, leave the planks clamped tightly in place.

15) Verify once more that the planks are tightly in place where they will live by gentle tapping with a hammer and softwood block and proceed to drill locator holes. Once the slippery bedding compound is applied it is impossible for clamps to hold things in place, the pre-drilled locator holes will do just that. A slight angle down on these screws will help pull the plank down to expel excess bedding compound.
I use Fuller tapered point drillbits and counterbores with matched plug cutters. These are available from Clark Craft Fasteners (1-800-992-5151).
In the vast majority of these antique and classic runabouts the average screw sizes in the hull are: Stem and Chines- 8 x 1-1/4”; Plank to frame - 8 x 2”; Plank to batten and buttblock - 8 x 3/4”; Plank to sheerclamp - 8 x 1”. These are the usual sizes, note the originals when you are disassembling your boat. Never re-use the brittle old brass fasteners, replace them with Silicon Bronze. These are available from many sources but
Clark Craft Fasteners appears to give the best quantity discounts.

The locator holes are drilled thus:
In the stem I drill all four holes. In all topsides planks I use two plank to frame screws centered 3/8” from the top and bottom of the plank. Note: for the chinestrake only, use one plank to frame screw at the top edge and one plank to chine screw that is not in line with the frame as it would hit the chine/frame carriage bolt. Set this chine screw at least an inch before or after the frame or frame knee. The butt joint will require four plank to batten screws.

16) After all locator holes are drilled you may remove these planks to your plank bench. Before doing any cutting on the top edge, sight carefully down the line you have marked with the fairing batten. Look for humps or hollows you may have overlooked because of the clamps. You should observe a smoothly curving, or “sweet” line. If there are minor adjustments to be made, use clamps and the fairing batten to mark them.
I trim this top edge with the jig saw outside the line and finish it off with a power plane leaving just the line. Practice this procedure on scrap wood until you are proficient. This is the surface the router will ride against to cut the bottom edge of the next plank so make it smooth and fair. Take care that this edge remains at exactly 90 degrees to the plank surface. This is very important, the router’s fence is set at 90 degrees and will automatically cut the necessary bevel in the following plank edge to fit the curvature of your hull. When you are finished shaping the planks, set the dividers at 3/8” and mark a line down the full length of the planks, top and bottom. This line will direct where to center your screw holes when you drill the remainder of the top and bottom plank fasteners. You will be surprised how many times you forget this step.
I seal the inboard side and all edges of these planks with two applications of Smiths CPES (1-800-234-0330), one immediately after the other. Set these aside to cure.

17) While the starboard first strake is curing return to the port side and repeat steps 12 - 16 on that side. Make sure you continue the fairing batten all the way to the forward point of the stem so that the planks are visually balanced from a front-on view. Take measurements up from the chine bottom at the transom to insure the same plank heights there. It would not hurt to check this measurement at a midships point as well. Set the port side planks aside to cure and return to the starboard side for plank installation.

18) Apply Mahogany colored 3M-5200 to the first strake chine, plank battens and frames. Trowel this application out so that there will be no voids left to hold moisture or dirt once the planks are permanently in. It is best to have a small amount of bedding compound ooze out from each joint to prove the absence of voids. You are the one who will be cleaning up the excess compound so learn early how much to apply. Usually 1 to
1 - 1/2 tubes will be enough for each strake, each side. More may be necessary in the chine rabbet depending on it’s condition.
Use clamps to install the forward plank first, using locator screws partially installed to get it in position. With the forward plank set in place and the locator screws positioned, yet not fully tightened, the excess bedding compound must be forced out as the plank is clamped down into the chine rabbet and forward into the stem rabbet. There are a number of ways of accomplishing this. Small 1” x 1” x 3” blocks can be temporarily screwed to the chine every foot or so to attach bar clamps to. This will work for the entire hull, if your barclamps are long enough. After the first strake, the chinestrake, is in you can use barclamps on the inside of the hull, from the bottom of the previous plank batten to the top of the next plank, providing you use a spacer to raise the clamp placement up from the top of the plank high enough to clear the next plank batten.
Actually, since the planks have already been dry-fit, and the router makes for such a perfect fit, edge-setting pressure is not needed to any extent greater than is necessary to simply remove excess bedding compound. For this purpose I have developed a tool I call a “step-jack” that I make from scrap plankstock. If it cracks or gets too dirty with compound, I toss it and make another. It is basically a 6” x 6” piece of scrap plankstock that I take to the bandsaw and cut a series of steps in 1/2” or so increments. The other piece of this tool is a prying arm about 18” or so that is tapered in width. With the step-jack set on top of the plank being installed, it is a simple matter to locate the correct step to use the pry against that will fit under the next plank batten. With one hand on the pry,
I can set and torque the screws. If I have to reach for screws with one hand, you might find me holding the pry with my chin or elbow.
In order to set the planks forward to tighten them at the hood end and butt joints I use a long barclamp hooked from the after edge of the plank to the next frame forward. I remove this barclamp as soon as the forward end is securely fastened as it will have a tendency to lift the after end of the plank.
Keep a ‘spooge’ board and putty knife handy to clean up excess bedding compound. Any compound allowed to set up in a bung countersink will not allow the bung to seat properly.
After all of the locator screws are torqued home you may install the follower plank in the same manner as the forward plank. Do not forget to apply bedding compound to the butt joint.
After all of these locator screws are torqued home you may drill and screw all of the remaining screws. The step-jack will still be needed for areas between frames and especially at the hull flare forward.
The screw pattern should follow the pattern in your original planks. Since the frames are never evenly spaced, the batten screws end up differently spaced in each frame bay. The easiest way I’ve found to make this look good is to take a measurement from one frame screw to the next with the millimeter side of a yardstick. Look at your original plank to see how many screw spaces the factory had in that plank and divide your measurement by that number. For example: if, in a given frame bay the frame screws measured 637 mm apart and there were 6 screws (7 spaces) in the original plank, you would divide 637 by 7 to obtain a 91mm distance between batten screws. Set you divider for 91mm and, starting at the center of one frame screw, tick off these distances one to the next. Remember to save these measurements for the same plank strake, same frame bay on the other side of the boat. A millimeter yardstick and hand-held calculator are much easier to deal with than inches and fractions.
After all screws are placed and this strake is in use a putty knife and scrap board and remove all excess bedding compound, especially from the planks top edge and batten and from the surface of the plank. It will definitely effect the operation of the router or the proper seating of the plank on the next pass. Use a respirator and rubber gloves and a xylol soaked terrycloth rag to completely clean all surfaces. I recommend cleaning interior surfaces as well. While not totally necessary, this will make it much easier to keep the bilge clean.

19) After you have completed and cleaned this side you may return to the port side and repeat step 18 there.

20) Install the buttblocks. The grain must be running fore and aft the same as the plank. Buttblocks should have chamfered edges and be spaced at least 1/8” away from any frame member so that water can drain into the bilge. Remember, if your boat is a pre-war Chris Craft, the buttblock was most likely fastened from the inside of the hull.

Repeat the above steps for each strake of planks. For most hulls the top one or two plank strakes, at least forward, should be steam bent onto the hull. This should be done early so that the planks have time, at least a week, to shrink back down in size before they are fit.
Leave them clamped to the hull as long as possible, until they are in the way of the planking operation.
These are the steps I follow when planking antique and classic hulls. It takes me longer to type out the explanation than it does to actually do it.
If I am uninterrupted I can usually complete the fitting and installation of one full strake all the way around the boat (four planks) in a single eight hour day.
Including the cutting of the plank ‘blanks’ and the steam bending of the top two forward strakes, the average 18 foot boat takes about 65 hours to plank. The transom should take another 10 hours or so but is usually not done until the deck has been planked. This is far faster than hand planing and fitting and results in a far superior, tighter plank job.

In the late 80’s I completely replanked a 55 foot William Hand Schooner with about 4000 bd/ft of 8/4 Honduras Mahogany. Even though I had become very proficient with a power plane, I still had to have a helper to carry these 50 to 80 pound planks up and down the scaffolding a couple times each to clamp and mark and adjust and eventually edge-set into place. There sat my 3-1/2 horsepower router, on the shelf collecting dust, a tool that would have produced the perfect fit, including the perfect bevel, in one pass. Had I the presence of mind to see this extrapolation, it would have saved this boat owner tens of thousands of dollars. I am reminded by this, every day, that there is so much more to
learn.

DANENBERG BOATWORKS DON DANENBERG
270 Third St.
Manistee, MI 616-723-9915 Fax 616-723-8309 ddanenberg@aol.com
__________________________________________________ ___________________________________

CAPTIONS FOR PHOTOS FOR ISSUE # 88 Don Danenberg

1) Diagram of router base

2) The hull should be plumb and level with supports to the floor to keep the weight of many clamps from distorting it.

3) Once a boats framework has been straightened, the old planks may still be too hogged out of shape to fit the hull correctly. Do not simply trace the old planks until you try the fit. They may be used as a spiling batten.

4) A heavy piece of 8/4 blocked up off your bench with 2 x 4s makes a handy plank bench you can clamp both sides of your plankstock to.

5) A clamp temporarily applied to hold up end of cutoff to avoid splintering under weight.

6) Planks are set for routing with spacers made to be 1/16” less than cutting height of router.

7) Larger routers would not clear the many clamps necessary to secure the plank.

8) The router fence guide rides along the bottom plank or chine to trim bottom of next plank to exact fit and bevel.

9) Router bit is set back just far enough to avoid nails or screws in plank batten, or to avoid cutting into the plank batten.

10) The remaining bit is quickly hand planed.

11) Clamps can be placed at frames or between them with the use of blocking across battens.

12) A high pitched whine can indicate a sliver of wood formed on rising grain. Cut this back to solid wood and proceed.

13) Fairing batten is first set at 1/2 batten depth marking.

14) Setting the fairing batten by eye is difficult though possible.

15) Continue fairing line onto stem so both sides match.

16) Practice with a power plane for quick, accurate trimming of plank top edges.

17) Pre-drilling locator holes allows exact placement after slippery bedding compound is applied.

18) A bar clamp is used to force planks forward during fastening.

19) A ‘step-jack’. A simple yet effective means of applying pressure while fastening planks.

20) The step-jack in use during fastening, forcing out excess bedding and setting the plank dead tight.

21) Planks can be pulled down with clamps to internal plank battens, as long as covering board is off.

22) Butt blocks should have chamfered edges and be mounted at least 1/8” away from frames or battens to allow water to drain.


Dave Greenup
posted 05-09-2000 02:26 PM
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Wow Don,
That's the way to do it. I thought there had to be a way to use my favorite tool to set the planks on my boat and now I can. You even
allow me to make mistakes and make up for them. Now that's a sound plan!!! I just can't
thank you enough. By the way I'll have to find an entire wall to hang the step by steps
on as it's 9 pages long and so detailed even I will have a hard time making a mistake if I follow them exactly.
Thanks Again,
Dave Greenup
Comox BC


PeterC
posted 05-09-2000 09:52 PM
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Don
Absolutely brilliant. Have read it through a couple of times now and it seems pretty clear, although a little worrying (exactly how many clamps DO you own? A couple of planks steamed, clamped and drying on each side, one for'd chine strake fixed, aft follower clamped in position, fairing battens in place, guides...SWMBO just ISN'T going to understand!). Still, the step-by-step, one thing at a time, everything in the right order approach sounds like even I could follow it. Have two quick questions though.
1. Do you still hold by the 'three strakes/three frames apart' rule for the plank?
2. I was planning on bronze riveting the plank on the battens (what are friends for, if not to hold dollies). Would you still set these in 3/8" from the edge?
By the way, a woodcarver friend of mine who uses a router "freehand" has the power cord running to a sprung feeder wheel on a boom attached to the roof of his shop - kind of feeds out and returns like a vacuum cleaner cord. Keeps the power cord off the floor and out from under his feet.

Don Danenberg
posted 05-09-2000 10:52 PM
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Hey Peter, I have a couple hundred clamps but I also have employees and 3-5 boats in progress at any time.
The Jorgensen 3706, six-inch barclamp is best for this procedure. You could probably get by with 20 if you worked one side at a time. You still have to plank sides equally though, get all of strake one done before going on to strake two.
If you're speaking of the Herreshoff 'rule of threes' for butt joints, NO, this is not necessary for batten-seam construction. The battens serve as longitudinal stiffeners themselves.
The articles I write for Classic Boating magazine are aimed at building or restoring Chris Crafts, GarWoods, Hackers, etc. These runabouts all have ~2ft frame spacing and 1-1/2" plank battens. Butt schedules usually fall 2 frames (4 ft) apart with 1 frame (2ft) not unusual. All fall within 4-inches of a frame.
The center of a 1-1/2" batten is 3/4" for the plank to land upon, half of that is 3/8". This spaces the fasteners evenly in the batten. Your batten width might dictate otherwise.
I have 110 and 220 suspended from multiple points in my shop ceiling. Its darn handy but I don't expect that from my readers.
You really should call Classic Boating and get issue #88 ($5). It has over 20 photos that add a great deal of understanding to the text. Have fun (remember to mark bung stock), Don

Don Danenberg
posted 05-09-2000 11:20 PM
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Peter, just tell SWMBO your clamp purchases won't exceed her cosmetics budget for the year. Some of those teeny-tiny bottles on her dresser cost as much as ten clamps easy.
Don

lee
posted 05-10-2000 12:00 AM
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I don't want to start anything, but I can see from some of the other topics that you guys seem to dig this.
Are you kidding this sounds exetremely cumbersome and complicated. Why not learn how to spile, tune up your band saw, sharpen your plane and do some woodwork. It is not that hard to do handwork. It is more fun and you can be pretty qiuck with hand tools once you are comfortable with them. Hand tools have been thought about a lot longer than power tools.
You could replank the boat faster than it would take to remove the old planks. (and if they are in good enough shape to make a pattern from why are you removing them?
Respectfully.

Ed Nye
posted 05-10-2000 01:32 AM
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Lee, I don't think they are repairing boats, but, restoring to a better than factory finish for scored shows. Opal is batten seam and her planks edges look great at 10ft. At 3ft you can tell they need work (maybe the next time she is wooded).
Ed

PeterC
posted 05-10-2000 02:02 AM
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Lee
Believe me, I appreciate the sentiment - the driving force (well, what got me started anyway) was the chance to work with wood with my hands again, to re-discover the pleasure, the smell, the satisfaction of creating. But it's also my personal homage to an era where quality counted, where skill was appreciated and valued, where pride in one's work was fashionable, and where time and the saving of it was not the be-all and end-all. It's why I hunted down original components (engine, drive, fittings etc.), why the boat will be riveted and why I continually take flack from well-meaning friends who suggest a more 'modern' way.
The difference in this case, I guess, is this. I am, like many, severely cash-limited. Young family, mortgage, new business etc. Not moaning, just the way it is. I literally cannot afford too much wastage of materials, especially the Mahogany (SWMBO calls my woodpile "the bank"). Being a first-timer I'm nervous about my skills, therefor any ideas Mr. Danenberg wants to share that can help in this regard are more than welcome. I don't say I will definitely use his method, maybe I'll just use the structure of the steps to work out a perfect spiling process, maybe clamp everything in place as suggested and mark up to the inside and outside of the new plank to get the shape and the bevel and cut it by hand. Who knows?

What I do know is that if someone has got a vast amount of experience, and takes the time to share it, then I will listen, avidly and attentively, every time. And then decide for myself what feels right for me. If you read through the article there are countless gems of information - where to put the strake so it will eventually drop straight down into the rabbet, where and when to finish the leading edge of the follower, even where to put the offcuts so you don't lose them. Lots of people tell you about the theory of building a boat, Don lets us in on some of the detail. And all of it is good.

The second reason this appeals is that this is my mid-life crisis project (she's called "M.Elle.C"). I would like to have her in the water while I am still old enough to get into the seat unaided.

As for Don, my guess is he's spiled and hand-cut more B.F. of plank than either of us has had hot dinners. The man runs a business, he does this professionally, and has got to make a buck or two. Anything that achieves perfection faster, with less wastage and saves the client money can't be bad.

Like I said, Lee, I do appreciate the thought. One of the greatest things I've discovered since starting out is that people argue, opinions differ, methods seems at odds, 'rules' get broken and still the most beautiful boats get built.

Seems like the wooden boat can survive us all!

Regards

PeterC

P.S. Don, when I say "vast amount of experience", that was in no way a comment on your age. I'm sure you can still get in the boat unaided.


Cedar Hill Boatworks
posted 05-10-2000 09:41 AM
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Don,
Thank you! What a great method. I have reread the piece a few times now and am fascinated by your approach. Is this your idea?
Lets carry it out a little further. On a lapstake hull, do you see any reason why this same method would not work if:
The plank to be routed were held up off the faying surface of the frames on spacers and a continuous batten. A second continuous batten tacked to the fit plank and used as the guide for the lower edge of the upper plank? The upper edge of each plank will have to be finished as you describe.
As you said there seems no reason why this method cannot be used on a carvel planked hull as well.
Thanks again.

Don Danenberg
posted 05-10-2000 11:12 AM
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This method (similar) was reported in Woodenboat magazine sometime in the late 80s by Ken Basset and Charlie Gath. It is now the standard of the industry for runabout restorers. Production runabouts were never built by hand-planing the plank edges, far too inefficient and flawed for varnished hulls.
Too many people nowadays tend to over-romanticize wooden boat building.
Production runabout builders like Chris Craft, GarWood, Century, Hacker and many others were built on an assenbly line bases.
All parts were cut in the mill operation to patterns. Planks were cut on router tables with appropriate patterns screwed to plankstock and passed through a shaper bit.
These precut planks were delivered to the planking assembly station and applied to the form. No hand fitting was done, There were no boatwrights on the line. Most of these tens of thousands of boats were assembled during the winter when farmhand labor was cheap. Luckily, records, photos, and even silent movies are available to show the procedures. I have a 1927 Chris Craft plant inventory list showing 32 Black and Decker drills and 27 electric screwguns.
From 1985-90 I had my shop in the Herreshof Marine museum complex (30 Burnside-first floor) where I learned the vast amount of power tools employed there, steam powered.
They didn't hand-fit everything in the 1800s and still were known for quality.
Cedar Hill, I'll ask Chris Smith (grandson of CC founder)how lapstrake gains were produced. They were most likely run through multihead shaper jigs as all their keels and chines were. Don


lee
posted 05-11-2000 09:47 AM
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hand planing or power planing plans is not inefficent or flawed. I have hung plenty of planks this way and have even had some varnished. Now granted i dont work on battenseam boats. I dont see this as a method appropriate for carvel. You would still need to plane on the calking seam and the plank thickness would be a deterent. By the time you had a plank set up to rout a conventional planker would be on the next plank. However an amature may not have the skill to produce a tight plank on a tight seam boat.
again I dont mean to be disrepectful but In eleven years of boat work I have never seen anyone plank with a router, it just sounds like a pain in the a. Also I would hesitate to call any method fool proof as I can screw anything up. your method seems to have a lot of set up and there are plenty of things to go wrong. I would like to see this method used sometime and will try to track down a copy of the magazine to see the photos
I know some of the old shops in Seattle had shapers that cut the plank edge and the calking seam all at once. They had a top bearing that ran on a batten that was nailed to the plank line. Of course these shapers had tilting arbors to swing the bevel.
I use a tuned up band saw acurate spiling, cut to the line and clean up the saw kerf with a sharp plane and you can not slide a piece of paper between the planks It is pretty fast too. I can spile and hang a twenty foot plank in a day and have they next one just about ready. However again this is on a carvel plank and if it was a tight seam boat that was not calked I would probally slow down. I don't think it is fair to classify traditonal planking as slow or inaccurate, there are plenty of examples of extremely fine work out there.
I dont know if an novice could hang a plank on a show quality garwood though.


Dave Greenup
posted 05-11-2000 03:20 PM
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Hey Don,
This idea is about what I was thinking would work for planking although I was a little
worried that it would not be accepted as
an submition for the forum for ovious reasons. Some people just don't understand that the wood that their hand planning has been cut down with a chainsaw trucked to a mill and cut and planned to the size that they can use, using machines. Get a grip there are just about a million other things to do when building a boat that can be done by hand and they all take time. This method does not completly remove hand tools if you read it. It still requires perfect honed edges on all of your hand tools and you still get to be close to the working of the boat. All that it does is give me a better chance to finish My boat rather than guessing, besides like I said "with My favorite tool".
I take great pride in all of My woodworking
and over the years have discovered many ways to acheve the same results faster using different methodes. The same sort of method is used by a friend to scribe counter tops to walls and get a perfect fit. All the joy
that I'll get from sailing My HAND made wooden boat will be all I need. Building a
boat is My hobby not My lifes work. If you have your methods written down I'd like to read them too. This buissness of building boats is so fasinating, is there a right way or can we follow some new direction?
Of course with out using something other than wood!

hope your all having a good day.

Dave Greenup
Comox BC


Don Danenberg
posted 05-11-2000 07:52 PM
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lee, I certainly did not mean to imply that your work or anyone else's was inefficient or flawed. I have been planking wooden boats for thirty years, the first 20 years mostly sailboats from 12' to 117'. The last ten years I have come to specialize in Mahogany runabouts, 15' to 30'. I consider them "models" because I no longer need hire cranes when I want to move a keel or horn timber or such. (my motorcycle knees dislocate in bilges, I hate bilges). The first 80 hulls I planked were hand planed, whether carvel with a 60%, 10 degree caulk bevel, or batten-seam carvel with no caulk bevel.
The last 40 hulls were planked using the router method. As Bob Cleek would say, 'ya gotta try it'.
Two planks a day was about where I was, hand and power plane, before the router; now it's double that with far, far greater accuracy.
Its not as cumbersome as my writing might make it look. Don


lee
posted 05-12-2000 02:24 AM
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don, as i said i would like to see this method. With all the clamping and set up I have a hard time understanding how it can be that much faster. I would love to see it maybe the next time i am in michigan i will look you up.
As i said before I plea ignorance in batten seam construction. I understand it, I have seen it but I have never done it. The next time I have a chance i will exhamine it closer. you had some excelent tips in your artical, such as saving the off cut for bungs.

PeterC is considering building a runabout. Even if it is off the plans of a production boat he is building it as a one off. The boats mentioned in this exchange have all been factory produced, "there were no boatwrights on the line." They were mass produced to be cheap. I am sure that the boats you have rebuilt are of a much higher quality than any was out of the shop.

these companys pre cut their boats like a kit, not because they were going to be varnished but because they were pumping them out, they were cheap. I am not saying that they were poorly made, ugly or anything sladerous. I just wanted it to be understood that Garwood, chris craft and others did not machine their planking because it was more accurate but because it produced a VOLUME of the identical piece quickly.

I think it is essetial for anyone considering to do woodwork the hull of a boat to understand spiling. I dont know which boat PeterC is trying to build or what quality. If he is a first time builder and he want to get a Show Quality perfect boat his first try you and I know that he will not succed with out a lot of time learning to use his tools, no matter which ones he uses.

I am not romantic about hand tools, Boats, woodwork or the old days. Where a power tool is faster i use it. router, motor beaver, skil saw, whatever. Where i have a hard time seeing how your method is faster is in the set up, all that clamping and getting a twenty or ten foot plank clamped on a boat evenly, with all the blocks. Not to mention getting the batten in there and taking it back to the bench....I would love to see it.

For Peter doing a one off, Just for his pleasure I assume I think it would be better for him to learn to spile. There are several books that cover the subject and perhaps macitosh has the easiest to understand. I will try to give a breif description of the way it is done at the shop I work at because it is pretty simple. There are a lot of ways to spile and once you understand what you are doing (and were you are doing it from) you will start to improvise.

For a plank first we go and record the bevels of the plank by picking up the angel of the plank edge to the Frame. Noting how the angle orients, either STANDING beyond square or UNDER square. Then we make a spiling batten or pattern from 1/4 inch ply wood. We cut these to fit in between where the plank edges will be. Screw it together . You can either lap the joints or cleat them.(For shorter planks 1/8 inch doorsking and hot melt glue or staples works.)

Now you need a spiling block. about an inch by one and a half or so. there should be a rabbet in it the thickness of your pattern stock. only a bit of the block remains full thickness just a quarter or so. I will make one that is a foot or so on the table saw and just cut it off and inch or so at a time.

the tonge of this block should fit between your spiling pattern and the ajacent plank, or rabbet if it is a garboard. run the block along the plank edge marking a line on the pattern. be sure and get the hood ends In addition I will often make a quick hood end pattern. Make a line locating each frames. with a pair of dividers make note of the width of the plank you are making. It helps to remember to note the old plank lines when wrecking out. Transfer the bevels to the pattern (inside the scribed line. With a band saw or jig saw cut to the line you just scribed. clean up with a block plane.

Now we will be working from the inside face of the plank so turn the pattern over and tack it on your stock (which should be best face out) Run your block around the line you cut. make notes of where the frames lie as it is here where you took and will orient your widths.

Here is where it can get confusing. turn you pattern over. you wrote on the outboard face of the pattern but you are drawing on the inboard face of the plank. Transfer your bevels making sure that they are on the correct edge of the plank.

Transfer your widths.a word about dividers I like a two point pair, not a compass though compass would work fine. When taking the width I do it at the frame. On my patten I place one point on the frame reference line and poke it in then I scratch an arch conecting the two with a line. Whe I lay it out on the back of the plank I poke it into the wood. One line is marked by scribing now with a batten I conect the dots that form the top line. I usually cut out the plank with a band saw as with a helper you can swing the bevel. but if I am alone I will use a skill save changig the bevel ever few degees. this is not as fast as a band saw. I use an ink pen or a sharpe pencil to layout so I know where my line is. I try to split or leave the line taking care not to loose it.

with a sharp plane useuall a no 3 or 4 I clean up the saw marks. Here is the beauty of the dividers. I can see when I am dead on because I have planed off exactly half of the hole that I poked. Some of the guys use a power plane to do that but I am more comforable with the hand plane.

If I had cut the plank with a skil saw the planing fairs through the bevels. then you lay out your calking seem and plane that it.

I will take the plank to the boat once to fit the hood in and if it is a shutter role it around to check the fit.I usually steam a plank right on the boat and will fasten it while it is hot. some folks like to clamp it abouveor below the hole.
I do a lot of shutter planks as I mostly am doing repair and after a few planks I hardly ever had to take a plank down because it was too fat and needed to be planed. It was not too long before it was hard to get a stiff piece of paper through. ( I still check myself)

I never really worried about shrikage. 95% of boats I work on are calked. I only see shrikage if the boat is out of the water for a long time, and it is just going to get wet again. Unless the wood is just sopping wet or the boat is going to be out of the water a long time the shrikage should be minimual. Sometimes they swell in the box but they srink back to size.

Any way you got me curious to try a batten seam plank. And like I said I would love to see this method if anyone near port townsend has a project where they are empoloying it. I am always curious.


PeterC
posted 05-12-2000 08:09 AM
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Lee
Brilliant. You were right about the confusing bit though. If I read you right you are transferring the bevels measured and marked on the outside onto the inside of the plank. Does this mean that as you are looking at the inside of the plank the actual bevel angles will be kind of 'opposite' to those marked on the pattern? (You know what I mean, in effect you're looking at the bevel backwards?).

You were almost right about the woodworking skills. Although I have worked in the building trades in the past it's been some years since I was seious about it and I'm rustier than an old plane left in the brine. I fully intend to learn to spile, the point of this for me is to learn and enjoy doing it. Compared to you guys I'm a babe in the woods, but you gotta start somewhere, and getting posts like yours and Don's is about the best way I know how to learn - straight from the horse's mouth.

Thanks again

PeterC

(Show quality? Might show my missus, I suppose, we don't have shows like that in New Zealand 'cause there just aren't really any of these type of boats here!)


lee
posted 05-12-2000 09:43 AM
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peter, when you take the bevel on the boat it is between the frame and the plank edge. If there is no plank on one edge I measure the bevel to a square and split the differnce. Try to make sure that when you get to a shutter situation that the inside of the plank is smaller than the outside. you will find that most bevels are standing from the inside of the plank.
Of course on your pattern you have to mark these on the outboard face. lets say when you lay your plank out the top edge of the plank and pattern are toward you. when you remove the pattern to transfer information the top edge will be away from you.

You will learn to trust your spiling and when you are doing floors, sole stringers, bulkheads it will be so much eaisier. I don't know how you could get on without it.Just always keep in mind where you are spling from and to.

as I said there are a lot of methods in many books. I like Bub Macintosh for it's great illustartions and readablity, it is like a conversation.

Good luck on your project,


lee
posted 05-12-2000 09:59 AM
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peter I just re read your queary and what to make sure that i answer your question. When ever i take a bevel i imagine it from where i will be laying it out. it gets too confusing at the bench. I imagine a cross section of the piece, a plank in this instance. if you measure that the plank has a ten degree standing bevel from the inside mark that on your pattern. there is no changing the standing or under, no oppposite bevel. Just make sure that you get the correct side of the plank when you transfer information Mark your pattern and plank top and bottom if you need to.
I hope that covers it sufficently. sorry about my poor typing skills.