nutshell pram

[sidneyhuskey]

I am currently in the process of building my first nutshell pram. (next boat will be larger i hope) Anyway, i am ready to make the daggerboard but do not have any half inch marine plywood and I hate to buy a full sheet for such a small piece. Have been considering just using a high quality pine plywood for now with the intention of making one our of marine ply one day with that next boat. My questions are...is there any thing i should do to protect the wood for soaking up water such as a coating of epoxy or varnish. the boat will only be in the water for the time i am using her. then she will be hauled out. Also, i have some 3/8" marine ply i could use instead. Maybe glass and epoxy that? Also, bedding compounds...can I not use 5200 or do i have to buy something specifically named bedding compound? I have never seen anyone specify what they use for bedding compound. Most will only say use the bedding compound of your choice.

Thanks

[Captain Pre-Capsize]

Here is what I did on my skiff: (Well, let's be candid - this is what the plans called for that I followed slavishly, and would do again).

I made my centerboard out of some one by oak. Not plywood at all - solid wood. I traced the outline from the blueprint, cut it out and then began forming it. This entailed tapering the leading and trailing edge, rather like an airplane wing.

When done it was coated with two coats of epoxy and then a few coats of varnish. It is essentially on it's trailer unless I am on the local pond or river. Seems to have worked just fine for me.

I like the idea of it being solid oak for those times that I am careening (note my moniker above!) around and run into untold buried obstacles. :D

[ 10-26-2003, 08:44 PM: Message edited by: Captain Pre-Capsize ]

[Venchka]

Got enough 1/4" marine plywood to make the daggerboard from 2 pieces epoxied together? Fiberglass & epoxy the board and the inside if the case. Makes those high wear & hard to get at places pretty bullet proof.

[Ocean Spray]

Just in the process of building our third Nutshell. For the daggerboard I also
laminated two pieces of quarter inch plywood together
with epoxy and even a layer of fiberglass between the
two to give it additional stiffness.
As for bedding the dagger board box, do not use
3M 5200..............if it leaks,you will never be able to get
it apart. Interlux makes bedding compound just this
situation.
For the mast I went to Homedepot and picked
through a new lift of eight foot 2x4's and found a couple
of really clear pieces. I let them dry additionally in my
unheated garage while we finished constucting the hull, and then we laminated them together and shaped them. It weighs about four ounces more than the expensive sitka spruce mast that we made for the first Nutshell.
For the boom and the gaff , I also went to Homedepot and went to the wood molding department and bought round pine hand rail. It comes in two diameters,one and half inch and one and a quarter. Nice straight grain and very flexible. Easy enough to taper with a small plane and some sandpaper.
It's a great little boat......fun to build .....rows and tows well and sails great........we've sailed them in over thirty knots of wind without sitting up on the rail !

[Nicholas Carey]

Originally posted by sidneyhuskey:
Also, bedding compounds...can I not use 5200 or do i have to buy something specifically named bedding compound? I have never seen anyone specify what they use for bedding compound. Most will only say use the bedding compound of your choice.FYI, 3m 5200 is not, repeat not, a bedding compound.

It is an adhesive — and an extremely strong one with the bonding strength of epoxy, albeit with higher creep and more flexibility.

"What 5200 has put together, let no man tear asunder" is a good saying to keep in mind.

If you want a traditional bedding compound, try "Dolphinite" or Interlux Boatyard Bedding Compound.

For a modern bedding compound, use a polyulfide produce. Some brand names are Sikaflex or 3m 4200.

You should be able to get these from West Marine, Jamestown Distributors, Hamilton Marine, etc.

[NormMessinger]

I hope you don't mind me expressing a couple of thoughts that came to mind as I read through this thread.

"I'm building my first Nutshell...." First? I thought you might have meant "first boat" but then I see Ocean has built three. Addicting aint it? That is one beautiful little boat.

A layer of glass between two pieces of ply wont add much stiffness. Of course this I figured out after I put a layer in the middle of the laminations for the boom on Prairie Islander in which case any added stiffness in probably nil. No harm done.

I feel better now. As you were...

[Keith Wilson]

For a daggerboard on a small boat, decent ACX fir or pine with glass/epoxy sheathing is almost as durable as the good stuff. I'd use glass; as well as making it stonger and stiffer it reinforces the epoxy layer and allows it to be thicker without cracking. And if it rots, hey, no problem, throw it away and make another one. It's not like it's part of the hull.

One thing about the Nutshell, it's a wonderful boat but it wasn't originally designed for homebuilders, and hence makes no attempt to use plywood sheets efficiently. Doesn't it use 1/4, 3/8, 1/2 and 3/4, partial sheets of the latter three? Fine for Joel White's boatyard, but hard on one's budget if you're building only one and have to buy full sheets. Making your own plywood by laminating thinner pieces with epoxy works fine, however. If you're going to put on glass, put it on the outside; like Norm says, a layer in the center adds no significant bending strength or stiffness.

I'll second the closet pole or hand rail stock for booms and yards. I've done that a couple of times and it works well. Around here they are usually nice clear douglas fir. Cheap and already round; what more could you want?

And if you're going to laminate a mast, luberyard wood is just about as good as any as long as you're patient picking through the pile. You can afford to throw away an awful lot of knots for the price of clear Sitka Spruce. Birdsmouth construction is easier than you might think, and really light spars are nice.

[ 10-31-2003, 02:45 PM: Message edited by: Keith Wilson ]

[JimD]

Yes, high quality pine or other plywood outta be fine. You may not ever have to replace it. Epoxy encapsulate it. Fiberglass is a good idea too.

No, like already said don't bed with 5200. Bedding compounds are flexible softish compounds to seal out water. They're not intended to bond surfaces together, 5200 is.

[JimD]

oops, missed one of your questions. No, don't substitute 3/8" for 1/2". The board's strength comes from the thickness of the wood so sheathing thinner plywood is no substitute for the planned greater thickness.

[Ocean Spray]

Speaking of substituting materials, in my real job I am a sign carver..........I recently took down a two and a half foot by thirty foot carved sign in Wellesley Mass. I usaully have to pay to dispose of these old signs. This one was constructed out of one and a half inch thick mahogany. The sign had shallow carving and no rot.
On my current Nutshell project, I have substituted solid mahogany for the three quarter inch plywood bow and stern transoms. I have also used this sign to make the laminated midship frame,the bow stem,the rubrails and the corner knees.
On one of the laminated frames, some of the deeper gold leaf carving can still be seen in the thin strips that make up the frame.
My other project is a Walt Simmons Duck Trap Wherry. The bow stem, cutwater and one inch thick transom are also made from this recycled sign. The inside of the transom also shows some of the deeper gold leaf carving.

[Scott Rosen]

WoodenBoat worked with Joel White to develop the Nutshell Pram specifically for the amateur builder. It wasn't meant to be a "cheap" boat, but rather a boat that could be built by a first-time builder with modest tools and skills.

WoodenBoat produced a book and a video on how to construct the Nutshell. In it, they recommend 5200 for bedding the daggerboard trunk to the hull and also the keel to the hull.

Having built a Nutshell myself, I can see the benefit of a strong adhesive like 5200 for the trunk, given that the bedlogs are not big enough to be through-fastened. If you do it right, it won't leak. If it does leak, you can remove the trunk by cutting the 5200 with a wire or a very thin blade. Not a big deal.

[Frank E. Price]

As a related aside, in my Nutshell I substituted a leeboard a la Bolger, hooking over the side, no pivot. No trunk to build, and the space where the trunk would have been is clear for stowage. The bottom is clean, which may contribute a bit to rowing efficiency, or not.

A board made from a board is stronger than ply, but mine is ply, and no problems. My 18' sharpy skiff however, has a centerboard made of boards, and again no problems.

Frank

[gary porter]

Sidney, I would not substitute 3/8" for 1/2" However despite that , it would work, especially if you glass it which will build it up a bit thickness wise. What will work and what is best is often two different things. The best thing is to go and buy a sheet of the good stuff and then lay away the rest for the next boat or build a nice planter stand for you wife or whatever. (Good points) I know many here have a hatred for 5200 but it will work fine and there really isn't reason for it to leak if you coat it well, let it set for a couple of days till its not sticky then clean up the squeeze out. You can speed up the process by using a spray bottle and mist the 5200 seam area and the squeeze out with water. 5200 needs moisture to set up or at least it likes it.
Wether or not the plans show it the daggerboard trunk can be notched into the seat, that is notch the seat a bit to recieve the trunk top. This stiffens up the trunk considerably. I really doubt that you will ever need to remove the trunk.
Give the whole boat a couple of good coats of epoxy, prime it, paint it, varnish what you don't paint and your good to go.
Have fun and don't take it too serious.
Gary

[ion barnes]

I have a 10' sailboat of undetermined pedigree. It came with two daggerboard designs, One of good quality marine grade and one of exterior Doug fir. Both were just varnished with exterior polyurathane varnish and had seen the elements for a longtime without much damage. I beefed up the edges by sanding lightly and giving a caot of same kind of vanish, let it get tacky and lay in a strip of 6oz cloth tape. Then begin to flood weave with varnish in successive coats till smooth. NEVER had a problem and its been twenty plus years with less than good care from me. I know its not a recogmended way but it worked and cost me very little.

As for a solid plank, dont go there. If it is of the wrong grain pattern, it could wharp and jam in the box. Good plywood, as in greatest number of plys possible (5 or 7) and exterior grade. Go to your lumber supply and get a partial sheet, we call them 'off cuts', and is a sheet cut into small panels of 4 x 4 or 2 x 4.