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View Full Version : Staggerd steps for scarphing-next step



chuckm
10-05-2006, 03:58 PM
Using Meranti ,1/2 inch and aligned 7 sheets in 6 inch steps for correct 1-12 ratio. Planed downed very nicely, then finished up with the belt sander. I have seen no voids and this technique works very well, except for sore mid back pain. Anyway my question; Should I glue the sheets together all at once? The 8 X 8 sheets all at same time, then cut. Or would it be easier to cut out as needed the dimensional plank, as needed out of the 8 foot sheet with diagonal scarph at each end, then glue. I can see where 4 x 16 feet of plywood could be a challenge to work. I know its all a challenge.

ssor
10-05-2006, 04:07 PM
Chuckm, your gonna need more than one helper on that stuff. I expect that it is bit enough to break if it is miss handled

MKane
10-05-2006, 04:13 PM
Well I am admittedly no expert, bit I would say glue them up whole. The alignment of the scarf will be easier and you may be able to make less sawdust by nesting the parts on the larger sheets.

That panel is only 4 x 15 ena half now anyway. :D

jlapratt
10-05-2006, 04:18 PM
Hmmmm, I would think that you'd have a difficult time maintaining the proper lines by cutting then gluing as compared with gluing then cutting. Even though gluing than cutting is more difficult.

Do I understand your post to mean that the scarph is stair stepped as in:
.|_
....|_
.......|_
..........|_
_______|

I thought I read where this type of scarph was "less than desirable" because it wasn't strong enough?

Jeff

MKane
10-05-2006, 04:25 PM
Jeff,
I think what he meant was that he stacked the sheets as in your illustration, then planed the edges to make a 1:12 scarf. Now he wants to glue them up.

RodB
10-05-2006, 04:31 PM
Your comments are kind of confusing....
Whats the finished dimensions of the panels you will be cutting out?

RB

Mike Keers
10-05-2006, 04:32 PM
My vote goes for gluing them up as whole sheets too. Easier to keep in alignment in my experience. I usually do it on the floor, with ply underneath, and use a couple-three drywall screws thru the scarf into the underlying stuff to hold it in alignment, then either screw another board down thru all for pressure, or pile weights on.

JimD
10-05-2006, 04:35 PM
The 8 X 8 sheets

Is this a typo? Do you mean 4 foot x 8 foot sheets glued in one piece to make a 4 x 16 foot panel? If so I think you may find it six of one and a half dozen of the other so to speak. Having one big sheet will make it easier to cut the final panel correctly but getting a good snug fair joint along a four foot plywood scarf can be a very tricky fitting and clamping job. I have had mixed success doing it that way. I have had very good success making long four foot wide panels using butt blocks but its too late for you to go that route. I have found that the narrower the widths of plywood to be scarfed the better the fit you will likely end up with.

This is a pic of a 4' x 18' sheet of occume with two joints in it and the joints came out very nicely but they are butt blocked, not scarfed. It would be a lot trickier to scarf such a sheet, at least it would be for me, a self confessed wood butcher.

http://www.imagestation.com/picture/sraid204/p5294c5e7797588e945d43de87a487dd7/ef51a543.jpg

chuckm
10-05-2006, 04:43 PM
thats right MKane, it's a traditional scarph, I was just describing the technique used to make them, all at once. The reason I'm asking is I saw a post a good while back. It was buiding Skerry, yea I remember It now. He's a very good novice builder who planked his scarphs on the boat in pieces. I have never read or seen it done that way. I need to find that site again. I believe it was a Oughtred C Yawl project. He used dry wall screws to temporarily position the plank, then he unassembled the planks and glued them together using screw holes as the guide. That way he was using shorter pieces of planking stock. I thought it to be very clever. Just tricky to arrange the peices.

JimD
10-05-2006, 04:55 PM
He used dry wall screws to temporarily position the plank,

If you're prepared to use screws this way the scarfing will go much easier. If you use drywall screws make sure you remove them before the epoxy fully cures. because they break so easily (but I bet you already knew that)

gert
10-05-2006, 04:55 PM
When I did the strakes for my 16' Shearwater I made templates of the strakes,indicating on the templates frame locations, nested these on the 4x8 sheets, rough cut the panels, step stacked and scarfed them, glued them together as req'd, cut them to the template back to back in pairs (port & starboard) then fitted-installed them to the frames. I positioned the templates on the frames so the scarf joints would be on a frame and always on a different frame from previous strake. I think by scarfing full 4x8s you limit your nesting and scarf location options.
I am considering gluing the scarfs on the boat for GS cause these puppies are going to be 25' long

chuckm
10-05-2006, 04:56 PM
I meant 4 x 8. I have already cut out templates from a lower grade 1/4 inch occume. Dry fitted this garboard plank to the keelson and was going to use this plank as a template to pencil in to the good stuff, The BS Meranti 1/2 inch ply. This template is 9 inch wide by 16 feet. These are still the short one's. I can't imagine working 24 feet long planks. So I'm trying to work out in my mind and with the lower grade 1/4 in occume how to plank on the boat as you go, with shorter 8 feet or less planking stock.

RodB
10-05-2006, 05:00 PM
The panels on my 18 foot skiff were...side panels 18' X2'
Bottom panels 33" by 18' 6".

http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=51640

I cut slightly oversized panels cross cut on the 4X8 sheets and glued up 5 pieces of 25" by 4 feet...to get a much stiffer panel. REsulting panel was 25" by 20 feet with four joints. All ends were scarfed and then glued up with 2X6 backing on the garage floor and 4" wide ply strips on top. Sheetrock screws did a great job clamping with wax paper inbetween stock and clamping material. A couple of staples were applied before clamping to hold both pieces in place.

When done, all joints are beltsanded and then the panel is marked for final shape via chalk line and cut out with a wormdrive saw with a steel plywood blade.

http://www.imagestation.com/picture/sraid70/pf697e498a952809c3cee33b6cc3b0dbf/fba287a9.jpg

I kinda thought that it made sense to only glue up panels that were slightly oversized from what you need and then do the final cut out after scarfing.

The only handling I had to do was lift glued up cut out panels up off the floor to set them on 2 X 6's laying atop sawhorses. Then I glassed the panels and assembled the hull on the cradle.

Edited to add...I didn't read the last two posts while writing this... so I guess this doesn't apply,... nevermind.

Oh yea, both bottom and side panels were cut similtaneously...goes without saying. According to Tracy OBrien, the designer, these multiple scarphed cross grain panels are much stiffer and really make for a better hull. Also, I did not have any problems with alignment ...ie., keep the glued up panels straight.

RB

MKane
10-05-2006, 05:04 PM
What are you building ?

Everything you have done so far is intended to make the alignment of those joints perfect. Why turn it from 3 scarphs into many ?

The method you mentioned sounds very labor intensive.

How about taking two of your panels and placing them together (finish side in) and cutting both sides at once. Keep them together as you fit them and get out on the water sooner.

chuckm
10-05-2006, 05:06 PM
I was thinking. You limit your stock and where you can position the planks when there "full sized" so to speak. To tell you the truth, I'm just scared to start the planking process.... I've never done it before :o and its expensive plywood. But I have the first garboard plank cut out in the lesser 1/4 in ply, just need to jump in and go....

chuckm
10-05-2006, 05:21 PM
This pic is about 6 weeks ago and have the keelson ,stem and sternpost all rabbited in now. The template garboard plank fits neatly in. I had to make notch like cuts in the oak floors and stern post. Will ask my daughter to snap a digital to get a further look.http://www.imagestation.com/picture/sraid211/pedf98434a178ef706ce85aa45922ddbe/ed7d13c9.jpg

Mike Keers
10-05-2006, 05:46 PM
Chuck,
If you have a template, and you're working with such narrow strakes perhaps that favors gluing the scarfs after getting the pieces out. I can't comment from direct experience as I've only done whole sheets and cut larger parts than you are.

OTOH, regardless of the care taken in planing the scarfs, getting really good alignment of the scarf itself can be tricky in my experience (but maybe I'm lazy about making them); having to keep to a pre-defined strake shape plus get the scarf right might mean having to favor the shape over the alignment of the scarf.

But like with most things, diff'runt strokes for diff'runt long boats, and you should do what makes the most sense and works for you.

I applaud your ambition in taking on the Seal, a challenging sized and satisfying project. I love the boat and gave it hard thought, but I have enough going on at the moment. Maybe someday....

Steve Lansdowne
10-05-2006, 07:37 PM
I'd get a helper, a large flat surface, and rig a jig of some type so that when you put the second sheet down over the first it is already (at least close to) lined up just right. Basically the jig is just some way of keeping the sides in a straight line and the ends of each from slipping backward as you put the second sheet over the first. Gluing together more than 2 sheets at a time (in pairs), while possible, would be more of a challenge.

Joe Lambert
10-06-2006, 08:10 AM
One eager vote for gluing up as panels and then cutting out planks. All the good reasons have already been mentioned but to sumarize, this lets you;
bookmatch the panels and make 1/2 as many cuts
deal with far fewer glue ups
do your gluing on a flat bench where it's easy to clamp rather than out of position on a boat
lay out your templates directly an confidently on the final material.

Get a helper or find a creative way to support the planks, you'll get a better product and probably be done sooner.

Good luck.

gert
10-06-2006, 09:09 AM
Chuckm:
You need 1/2 x 1 temporary "battens" tacked on the stations at the "lands" in order to bevel your strakes, these are also helpfull in making your templates but are essential for achieving fairness.
http://http://www.flickr.com/images/spaceball.gif

chuckm
10-06-2006, 10:09 AM
Its a beut of a weekend coming on. I'm hyped and ready so I'll post Monday hopefully with a pic. Thanks again chuckm:)

garyspear
10-06-2006, 10:47 AM
my vote is cut the strakes and fit them to a template this way you can cut angled scarphs and save plywood. it went pretty easy for me. Instead of 12" to 15" pieces cut from the plywood to get planks for my caledonia yawl. I was able to cut 9 to 9.5 inch wide stock from my plywood. these are then mitered and scarphed to get planks. should have taken a full 8 sheets but it took 7 instead.

here are pics of this process from a friends site.

http://users.rcn.com/mainerd/My%20CY/

that should be a good two cents worth.