Lofting the Brewer catboat

[Jim Ledger]

If there's any moment that could be called a beginning, I guess this is it. The lofting surface is down, sixteen sheets of quarter inch luan with two coats of flat white paint. Like a big, blank sheet of paper without a mark on it.






I'm sharpening pencils while the paint dries.

This is gonna be good.....

[Paul Pless]

This is gonna be good.....

Yup!

[MiddleAgesMan]

If you document this cat boat project half as well as you've done with your other threads "good" isn't the word I would choose.

FANTABULOUS would be a better word.

[Texasgaloot]

I just got band saw envy...

[Kaa]

Such a Zen moment... :-)

Kaa

[P.L.Lenihan]

What's with the chain block running athwartship? And yes, this is going to be a grand thread once ya get rolling

Peter

[Jim Ledger]

I just got band saw envy...

Already? Maybe you shouldn't watch any further.


Peter, the chain is pulling the knee wall on the left side of the picture back into plumb. Over the years, the pressure from the bows leaned it out a bit. I'm replacing the plywood on the sides with T-1-11 and straightening it out as I go, backfilling the posts with some concrete..

[Paul Pless]

Quote:
Originally Posted by Texasgaloot
I just got band saw envy...

Already? Maybe you shouldn't watch any further.

ROFLMAO!!!

[kc8pql]

Almost makes me want to start another boat. Almost.

[paladin]

naw....after the 2nd and third time it's anti-climatic and ya just want it finished and in the water........damn nice looking lofting surface, jim.....

[michigangeorge]

Jim, how are you keeping that luan flat? All the 1/4" stuff I've been using wants to warp or otherwise move about and not lay flat - and that is on a heated floor of consistant temperature.

[Ian McColgin]

Super work space.

Is this Marmalade's sister, a Chappequiddick 25?

[Mrleft8]

I just got band saw envy...

Mine's bigger......
I'm seeing a potential book in the making.... This is gonna be a keeper...

[Jim Ledger]

Super work space.

Is this Marmalade's sister, a Chappequiddick 25?

Yes it is,Ian, a sistership, another Chappaquidick 25, and I hope you look favorably on the project. Any advice or comments you might have will be most appreciated.

[Jim Ledger]

Jim, how are you keeping that luan flat? All the 1/4" stuff I've been using wants to warp or otherwise move about and not lay flat - and that is on a heated floor of consistant temperature.

It could be flatter, I'll admit. I replaced one piece because of ripples, but I think it'll be OK from here on. Masonite might have been a better choice but I want to store the sheets on edge for the duration of the project. Masonite tends to bend when stored in this manner.The sheets will be numbered for reference so I can easily pull the ones of particular interest.

[Ian McColgin]

Let's talk about the centerboard pendent, and I much recommend a solid wood, heavy mast.

[Jim Ledger]

Let's talk about the centerboard pendent, and I much recommend a solid wood, heavy mast.

Black spruce seems to be the traditional wood for a catboat mast , no? I don't believe that they grow here on Long Island but more to the north in New England. I'll have to look for a source.

The centerboard and its case have been much on my mind lately. It would seem that an early decision must be made before the keel's ordered. The plans show a triangular board of 3/8" stainless steel in a 7/8" wide keel slot. That's 7/8" through 12" of timber. Not impossible, but not easy either. The issue is, though, the cost of the stainless board. It's astronomical. A traditional wood board could be made at a fraction of the cost.

Which would mean making the inner portion of the keel wider to accomodate a wider CB slot.

I'll get around to the pendant shortly. Be back.

[paladin]

Having worked a bit with Ted Brewer/Bob Walstrom/Jim Betts......Ted Brewer draws nice boats.....

[Jim Ledger]

[quote=paladin;1831041.Ted Brewer draws nice boats.....but I dunno think anyone has ever accused him of drawing one easy to build...[/quote]

It's not just the difficulty of cutting that slot. If I wanted to cut it, I would. Just might take a bit longer.

And if I thought the stainless board was the way to go then I guess a way would be found. Remember, I won't actually be needing it until the very last thing. A template would do just fine for now.

The problem is that pennant. Ian's thinking of the top end, I'm thinking of the bottom. What I'm wondering is "how do I attach a quarter inch stainless cable to a three eights metal board inside a seven eights slot without a fitting at the attachment point that will end up scraping the inside of the case every time the board is raised or lowered.

The trunk sides are specified as 1" marine ply, something you don't want to abrade too much. Again, through bolted solid wood, for the case sides, might be, if not easier, then more durable.

[Ian McColgin]

Jim's ruminations are spot on. There's a glass Chappy 25 that fixed this but I've not dug into Marmalade enough to figure if his fix will work for me. My board sticks a several places and I think it's due to the thimbled eye in the cable twisting.

My board is steel, not stainless.

I've not had the problem yet that I've encountered in other metal boarded boats - bendin the board. But it's a real issue. Marmalade cannot really be modified to a wooden board, which I think superior, but new construction might. A wood board for a boat of this tonnage needs to be 3/4" to an inch. Is it worth it? Don't know. I've taken the ground pretty hard on a beat in seas and not bent it yet so maybe my paranoia is not justified.

More thoughts as they come.

[Duncan Gibbs]

What about a "flat" hinge? Think of having two fat "washers", one welded to a lug and then bolted/welded to the board and one with a groove ground out of the edge with the cable wrapped around it and crimped/whipped and the two "washers" held flat together with a pin peened at both ends. A teflon washer could sit between the two hinging "washers" and teflon could also case the entire connection ensuring it never jams inside the case.

Whaddaya think of that?

[Kaa]

The problem is that pennant. Ian's thinking of the top end, I'm thinking of the bottom. What I'm wondering is "how do I attach a quarter inch stainless cable to a three eights metal board inside a seven eights slot without a fitting at the attachment point that will end up scraping the inside of the case every time the board is raised or lowered.

I had a similar problem, this thread -- http://www.woodenboat.com/forum/showthread.php?t=78573 -- might be of interest to you...

Kaa

[Jim Ledger]

Bending a 3/8" steel board would take quite a blow and I'm not sure something else might give out first. But, having the boat heeled over and getting pushed by waves onto a sandbar can put some stress on a board and case.

Sea Rovers original board was 1 1/4" thick with a 1 3/4" slot. The bottom aft corner had been rounded to a large radius over the years. Four boards, drifted together, not one board less than ten inches wide, and not one drift that went through more then two boards. Maybe it was built to flex, cause I'll bet it did.

For those that might be interested, the centerboard and case in this design are somewhat unusual , though not quite traditional. Instead of being rectangular, the board is basically a triangle, about seven feet along the bottom and about five and a half feet high along the aft side. The immediate advantage is more useable cabin space. With the front edge of the case sloping down it opens up the floor space. The board fetches up against a positive stop at its lowest point of travel, still leaving about a foot of board inside the keel.

Anyway, Ian, I'd like to hear what you have to say about your experience with this board. We'll get around to the placement of the winch sooner or later.

[holzbt]

Hi Jim,

Having had both metal and wood boards in a number of different boats, I would definitely prefer wood. A metal board requires a winch or some sort of hauling tackle and also presents the problem of the pennant in the narrow case. A wood board can usually be hauled by hand or with a simple tackle, costs less to build and is less likely to bend if you touch bottom. (And we both know THAT NEVER HAPPENS in the GSB.)

Another thing to think about is the trunk placement. I know that the 25' cat designed by Fenwick Williams has an offset trunk as well as some of Charles Wittholz's catboats. Larry P's Antigua aslo has an offset trunk if you'd like to see one in the flesh. Building the trunk alongside saves cutting that slot right through the middle of the really nice stick you just paid big $ for. It might not be worth the design modifications depending on how Brewer has everything tied together down there, but it's been used in many more boats than most people are aware and works just fine.

[Jim Ledger]

Thanks for the thread, Kaa. That's exactly what concerns me. And when you consider that the metal board weighs three hundred pounds then you get some idea of the problem. This particular junction endures a lot of stress and it must be made extremely fail safe. A catboat with its board down couldn't return to shore around here and raising a heavy metal board with a broken pennant would most likely be impossible without the proper equipment.

Things just seem more straightforward with a wooden board.

[Alan Peck]

Looking forward to following your lofting progress.

By the way, your shop looks like something I might like to try. Could you give some details on the ribs and the type fabric you are using.

Also, how are the ribs attached at the bottom.

[Kaa]

Thanks for the thread, Kaa. That's exactly what concerns me. And when you consider that the metal board weighs three hundred pounds then you get some idea of the problem. This particular junction endures a lot of stress and it must be made extremely fail safe. A catboat with its board down couldn't return to shore around here and raising a heavy metal board with a broken pennant would most likely be impossible without the proper equipment.

Well, the rigging toggle worked very well for me. It's narrow enough and has a sufficient reserve of strength, given that its primary function is to sit between a shroud and a turnbuckle.

The advantage of steel is that it's more weight way down. The trade-off for the wooden board is the need for more ballast which sits higher up.

Kaa

[Jim Ledger]

Hi Jim,

Having had both metal and wood boards in a number of different boats, I would definitely prefer wood. A metal board requires a winch or some sort of hauling tackle and also presents the problem of the pennant in the narrow case. A wood board can usually be hauled by hand or with a simple tackle, costs less to build and is less likely to bend if you touch bottom. (And we both know THAT NEVER HAPPENS in the GSB.)

Another thing to think about is the trunk placement. I know that the 25' cat designed by Fenwick Williams has an offset trunk as well as some of Charles Wittholz's catboats. Larry P's Antigua aslo has an offset trunk if you'd like to see one in the flesh. Building the trunk alongside saves cutting that slot right through the middle of the really nice stick you just paid big $ for. It might not be worth the design modifications depending on how Brewer has everything tied together down there, but it's been used in many more boats than most people are aware and works just fine.

How've you been, Roger?

I think that even a wood board will need a substantial winch in this case as something that size, weighted to sink, will weigh, if not three hundred pounds, then not too much less.

The offset case is an interesting idea but I don't think I'll go that way. I don't have any qualms about cutting through the keel and I don't want to stray that far from the design. Still, I wouldn't mind having a look at one or two. Just to get an idea how it's done.

[Jim Ledger]

Looking forward to following your lofting progress.

By the way, your shop looks like something I might like to try. Could you give some details on the ribs and the type fabric you are using.

Also, how are the ribs attached at the bottom.

There's a few more pictures here...

http://www.woodenboat.com/forum/showthread.php?t=77323

Alan,

Google "greenhouses" and you'll find lots of steel framed designs available. The plastic is doubled 6 mil, 4 year poly, which has lasted more than ten years and might need replacing in a few more. The bottom of the steel frames just sit in bored holes in that 4 x 6, nice and simple. Soon, I'll put a shade cloth over the whole thing to keep the temperature down.

[Alan Peck]

Jim; Thanks

[Alex Low]

Oh man... that is such nice light in there. Will be a joy to draw in that space.

Alex

[Ian McColgin]

What was I thinking. Of course the board would be 3" or so if wood. Goblin's board was marvelous. One day we took the ground on a hard beat. The sideways strain jammed the board in the trunk so we came to a stop much as a keel boat would, except the board had deflected a bit on impact and as the stresses settled we could feel Goblin give a little shake as the board straightened back up.

A friend with a cute little dutch sloop with metal board took the ground and, not realizing what happened right away, was surprised when he could not wind the board up. Just a slight bend but enough. We eventually got the board out, toasted it for hours in the coals of the world's best beach bonfire, and then sledgehammered it straight.

Goblin's board was more than half below waterline when up and weighted just enough to bring her down, so it was handled with a three part tackle. I was surprised at my first haul-out how heavy the thing was out of water and needed a jack assist from below to get it back up after scraping and painting.

For we who take the ground, there's much to be said for a board off-set from the keel. The structure is stronger - no panting of the keel at the slot - and you're far less likely to be jammed up with stones and such. But in a Chappy, the off-set would make for some novel accomodation problems - resolvable I'm sure.

Marmalade's CB pendant passes over a pulley and back through the back of the cabin to a winch mounted on the foreside of the cockpit. I did not like this when I got her but have yet to come up with better. I can't think how to give room for it to level wind if I mount the winch right atop the trunk at the companion though that's my favorite bright idea - exept for one thing.

With Goblin I found real value to having a bungee at right angles to the pendant to take up any slack when we took the ground. This keeps the bight of the pendent from jamming between board and trunk. With Marmalade the bungee comes down from overhead and doubles rather well as a holder for paper towels - convenient to galley and cockpit alike.

[Ron Williamson]

Jim
On that CB/pendant attachment issue,you might think about the way that bicycle brake levers have their cables attached and get a keyhole slot milled into the top edge of the board.
Another option would be to attach the pendant conventionally, cut windows in the sides of the CB case along the arc of travel then cover them with 'inspection' plates.This would provide side clearance as well as access.Unfortunately it may weaken the structure too much.
R

[Ian McColgin]

The attachment problem is that the thimble and the loop welded atop the board are in the same plane and any connection, whether bike-chain type or shackle, is normal to that and tends to jam. The one solution I know of invovled making a flat landing at the bottom of the thimble and the top of the loop and then stitching really stout dacron webbing as the connector. With two full wraps, the web will hold by friction so long as a good row of stitching is put in the narrow space between thimble and loop. Given the build-ups to make flats inside the loops, this arrangement remains upright even if the board is coming up on a grounding with slack pendant. It appears no more subject to trouble than you have from galvanic action and corrosion with the normal pendent-shackle-loop connection.

The bike-brake type idea won't work because the angle of the pendent to the board changes as the board goes up and down. You're stuck with a localized hard spot unless you bring the cable down the back of the board a ways, round the upper rear on a 6" or so diameter, notch that so the wire will lay there, and figure out how to keep the wire in there when the pendent goes slack on a grounding.

Jim, on the stitch deal, the guy in the Catboat Association with the other Chappy 25 up this way did this. If you're a member, try finding him in the book. Or let me know and I'll make my often foggy brain work well enough to look it up when I'm on Marmalade this afternoon. He lives in Wareham of there abouts . . .

By the way, I've written elsewhere that the contrast of his boat and Marmalade is an interesting study in weights. He has lightish aluminum spars while Marmalade's solid stick is well over 600#. Catboat hulls have such powerful form stability that this weight aloft does not meaningfully add healing moment. The down-side of form stability is that the boat reacts strongly to waves, rolling with them. Marmalade's heavy spar dampens the roll amazingly while this other Chappy bobbles in mild chop light wind and thus spills her air. While a lesser sea dog than this other guy, I'm a better, at least more attentive, racer but the size of my lead when we've met has more to do with this bobbeling and air spilling than anything else. Even ifBrewer approves aluminum or light spars - he must as that's how the glass Chappy's are sparred - it's good you plan to stick with wood.

[Jim Ledger]

Is it true that there's an aluminum catboat mast out there that's faux wood-grained. I'm hoping to stick with the more traditional methods, in part because it might be easier and because the wrinkles have been mostly ironed out. I like the solid mast though I might be tempted to go with birds-mouth should a suitable pile of wood present itself.

As for the centerboard, the opinions seem to be running towards the solid wood board, which is in accordance with my thinking. How thick is the next question. Are you, Ian, and Chuck, suggesting a 2 1/2 to 3" thick board? That's way more than I would have thought possible. I was thinking that1 1/2" would be the upper limit, in a 2"slot.

Here's a picture of Kathleens keel with the slot being cut. Looks to be about 2"
http://www.beetlecat.com/28catboat/pic04.htm