Planning a glued-lapstrake Pete Culler Wherry

[HughRBeyer]

Hi guys -- this past week I pulled out an old set of plans I have for Pete Culler's "wherry yawl" and thought I might build the thing. It's about 10', lapstrake, plank keel, but deadwood skeg aft, no box skeg to plank. But I want to build it glued-lapstrake because there's no way it's going to live in the water.

Seems like all kinds of traditional boats are being built this way and there shouldn't be a problem, but what do folks here think? Are there dragons I should know about?

The plans call for 3/8" plank--I'm thinking I could reduce this in plywood a bit. Pete talks about how the boat might come in too heavy and if I can save weight here it might be good.

Anything about fastening planks to transom? I'm not sure how a dimensionally-stable set of glued plywood planks mates with a dimensionally-unstable solid wood transom, but the Whisp is built that way and the one I built 20 years ago is still solid.

Any advice welcome.

Hugh

[Bill Perkins]

Hugh : have you seen " Skiffs and Schooners" ,and John Burk's "Pete Culler's Boats". Both have information that I think you'd want to see before building . The details on the plans are minimal , if they're like the set I built from (a 24 footer ), so it's especially useful to read commentary by Culler . I reduced the plank thickness 20% and planked glued lap with no problem .

Is your boat set up like mine :straight keel ,curved stem ,with a substantial curved knee joining the two ( I know you've got some deadwood too ) ? I laminated the keel up with 1 in. ( max) thick stock to insure stability of that piece . The stem and knee were laminated with thin lams over curved forms ; again not sawn out of solid stock like the original . The idea is that the glued lap construction needs the most stable base we can provide . It's my understanding that the big solid sawn pieces would sometimes change shape a bit as they dried in place .

I cut out the stem and knee as Culler drew them , then bolted and glued them together ,along with the keel , over the lofting ,which worked fine . It later occurred to me that I could have saved labor and material by incorporating the knee into the stem lamination .Then you're just joining one curved piece to the straight keel . If we're going to laminate it probably doesn't make sense to make up the knee as a separate piece . You could always saw the finished piece to the designed inboard profile if you wanted that detail .

Rather than cut a stem rabet I made up an inner and outer stem. The outer stem is glued on after the planks have been sawn flush (athwartship ) the inner and outer stem haveing been seperated on the lofting at the inner rabet . The outer stem can be laminated right over the inner stem .Because the outer stem is deep on Culler's boats I also bolted it on to reinforce against sideways knocks .

It's been said ( I think by Chapelle) that a bright transom will tend to make a painted hull look shorter ,which I don't think you'd want on your some what plump little boat . Whether a solid sawn transom is a good idea structurally I can't say .Maybe the plank would be glued with a mastic adhesive there ? Maybe 4 oz. glass could be used inside and out to help stabilize the transom ? I epoxied and screwed my planks to a plywood transom ,laid up a bit thicker than the lumber original .

Sometimes a solid sawn sheerstrake ,finished bright , is used on an otherwise glued lap plywood hull ; not glued in of course . The idea is you may not care if a few drops come in when the boat is rail down on a breezy day . More than that will be coming over the side as spray anyway . Bill

[Keith Wilson]

I haven't seen any problems with fastening plywood planks to a solid wood transom, but if you're nervous about it one solution would be to make a plywood transom framed in solid wood like many of Iain Oughtred's boats. It looks good; there's a lot of opportunity for creative ornamentation in the shape of the framing. 1/4" or 6mm ply would work fine on a boat that size.

[HughRBeyer]

Bill: Thanks for the ideas. I've got Skiffs & Schooners, along with Culler's other books. "Pete Culler's Boats" is the book of designs, right? I've got that too, and there's lots of great info in there.

The construction details provided with the plans are, um, economical. I've been fleshing them out with Chapelle, who isn't all that much help, and Gardner, who's great. Culler shows both a one-piece keel connected as you describe to a one-piece stem, but Gardner suggests both keel and step could be built up so there's no rabbets to cut at all. This feels like cheating to me, but is probably the smart way to go.

What wood did you use for your stem? I'm thinking spruce from staging lumber. I potentially have a source for oak knees (we're clearing some land) and it might be that I have to use some of those for the saltiness factor.

Stupid question: if you bolt the stem on, how do you cover the hole on the outside? Big-ass plug carved to the stem profile?

I love the idea of a solid sheer strake.

Keith: The Whisp's transom does have vertical frames on each side which is what the laps are nailed to, as does my Buzzards Bay Sloop. So that sounds like a reasonable way to go.

[Bill Perkins]

I laminated my stem up out of clear Douglas Fir ,which I can get intown . The width of the forward edge of the finished stem I scaled from the drawings and selected flat head machine screws with a head diam. just a bit less . These I countersunk slightly . Culler , as you probably read , used Sassafras for his .

[Keith Wilson]

For details of glued-lapstrake construction, I'd suggest something in addition to books on traditional construction. Iain Oughtred Clinker Plywood Boatbuilding Manual, is very good, and possibly Tom Hill's Ultralight Boatbuilding. I haven't read John Brooks' book, but it seems very complete and may prove to be the best of the lot.

Oughtred:
http://www.woodenboatstore.com/prodinfo.asp?number=325%2D116
Hill:
http://www.woodenboatstore.com/prodinfo.asp?number=300%2D210
Brooks:
http://www.woodenboatstore.com/prodinfo.asp?number=325%2D120
A sample of Brooks:
http://www.woodenboat.com/books/BrooksSample.pdf

[HughRBeyer]

I've got Ultralight Tom Hill's book and I'll go hunting Ian's.

I'll cruise the lumber yards for fir, thx. I don't think there's any sassafras coming off the property :-)

[Bill Perkins]

Here's a great resource for locating the local lumber .

http://www.woodfinder.com/

Sassafras is widely available on the East Coast.

The Fir I mentioned is a cut above construction grade that you'll find in most lumberyards . Maybe check some outfit that's selling trim work and finish grade lumber . It's stronger and somewhat more rot resistant than Spruce .

[HughRBeyer]

Oh my god, I love the web. I can't believe that site. And thanks for the info about the fir, I didn't want to ask. :-)

[HughRBeyer]

Hey guys, another question about this project--

What's the best way of fastening the backbone? I've been looking through similar projects (Ellen, Tom Hill's book, the Catspaw) and it seems like everyone who's doing glued-lapstrake goes ahead and epoxys everything to everything else. Is that the right way to go? I'm tempted to use bedding compound (maybe do like the Cap'n says and use roofing tar) and screws for the backbone and for attaching the strakes to the stem, keel, and transom, and use epoxy only between the laps. But I've also no interest in innovating--if epoxy everywhere is what works, that's what I'll do.