Beginner Little Crab

I received the plans from D.H. Hylan for the Little Crab. My son(6) and I have the summer together and I'd like to get the boat together so we can take it out before he goes into first grade. We are looking to build a row/sail version.

Here's the problem: I open them up and I only have the slightest idea of what anything means. I sat in the lumber store wide eyed for 15 minutes staring at the building jig page before I walked out.

I know this boat, if well-built, will be an experience for he and I for years to come. Any help would be appreciated.

 

You should have a Bill Of Materials that lists what you need to build the boat. That is what you will need to buy. It is a modern design built in an old(er) fashioned way. You should have full sized patterns for the Jig, all you need to get is some cheap wood (lowest grade lumber) to build the jig with... no need to spend the budget on something that isn't part of the boat. I suggest you DO get good marine grade plywood and use quality lumber for the actual parts of the boat though. It will pay dividends in the longevity of the boat. It is big enough that It won't ever be outgrown as a 1 or 2 person knock about or a tender for a bigger boat.

 

Yes, I know that cheaper wood for the building jig. My trouble is that I don't know how to translate whats on the plans into actual physical construction. I got a book, Building Small Boats by Greg Rossel, from the library and will be looking through that later today.

 

The book is a a great start, but also check out the useful youtube videos on the subject.



The main points are

1) Build the frames

2) Mount the frames straight and at the right spacing

The trickiest bit for a new builder is that the distance between frames depends on whether they are before the widest bit of the boat, or after the widest bit. This is because the longitudinal lengths (stringers) 'land' on different edges of the frames.

I hope this diagram with exaggerated frames helps explain it.

 

Welcome to the Forum.

I'd agree with the other posts above. Any old stuff, like MDF, Chip, cheap but stable timber is fine for frames.

One of the trickier bits for beginner builders is setting the horizontal Datum so all your frames are vertically at the correct height from the floor. Almost no floor is level so you need to work out a system to set up the frames. Once they are locked out and solidly tied together, you can have confidence that the end shape of the boat will be fair and accurate.

If you research setting up the frames, you may find a method suitable for the floor you have to build upon. I have built with the frames on wood and concrete without too much trouble. My recommendation is to place a Datum line along the C/L of the craft but through the frames so you can ensure it stays level throughout the build. This means above the sheerline of the boat, which in the normal upsidedown build is closer to the floor.

As rwatson has pointed out, wisely above be aware of the frame stagger and also the curvature of the hull planking when setting up the frames. Be prepared to bevel one face so it sits correctly.

 

Finding a really straight piece of lumber is rare. Woodshops re-saw, re-plane and edge dress even fine furniture grade lumber when building cabinetry and stair railings, ect.-- items that need to FIT!
Steel on the other hand can be got cheap in straight pieces. The base of your building jig is probably 2x6s or 2x8s. rough lumber for rough construction. Buy a couple of lengths of 1.5X2 inch angle iron and screw/bolt/fasten to upper edges of your wooden base form will bridge any irregularities in the wood not being straight and flat. The iron angle is a perfect 90 degrees and straight. Don't force the steel to conform to the wood or you defeat it's purpose.
If you start straight and true, everything afterward is easier. Welcome and good luck.
An exception regarding straight lumber. Plywood and MDF FULL 4X8 panels. Edges are straight and square to each other. Untill it's cut, then, who knows.

 

Sorry... I gonna have to disagree with some of that. I work with various kinds of steel daily and frankly I rarely see a straight piece of angle iron that is of any decent length. We get our stuff in 20 ft lengths and it bends and sways all over the place. This is 1/4" thick 2"x2" angle here and I have seen it take a 3" or 4" set when leaned against a wall or otherwise had bowing pressure placed on it. You have to check the stuff just like you would a piece of wood. You also have to treat it properly. If you bolt it to a piece of crooked wood...it won't necessarily straighten that wood...more like bend to conform.

 

I wasn't suggesting the wood would be straightened by the steel. I DID caution against letting the steel bend to the wood. The boat the Op is planning to build, probably uses a 4 foot to 6 ft box base form to erect the frames on. my suggestion, one I've used my self, is install straight edges slightly above the wood. 4 ft and 6 ft angle can be purchased at most hardware and building material centers in USA, and all I have purchased were straight. a 20 ft iron noodle is a different animal!
But, your exception noted. The OP is advised, opinions are only opinions. Especially mine!

 

Back to the question. I expect the building plans has no steel in it so we don't need to argue about the merits.

Can you expand on the question?

"No idea" doesn't let us know what is confusing.
Do you have a materials list?
Do the plans show the dimensions on the building jig?

 

Sorry... missed that little tidbit . Yes... in shorter lengths it would probably be straight enough if you paid some heed when purchasing to get some with no kinks.

 

OP might not be aware he can post files. I only intend to be helpful, not pirate his thread. His Little Crab project details below. http://dhylanboats.com/littlecrab_plans.html

 

If the plans for a supposedly simple boat can't be understood, I'm thinking the plans are bad or the builders abilities aren't up to it.

If the plans could be posted, all sorts of specific help could be given, but bought plans shouldn't be posted.

You should tell what woodworking abilities you have and what tools you have.

If you want to have a boat done before school starts, the idea of building an heirloom boat should be put aside. A 6 year old doesn't have the attention span for a 'long term' project and won't care what kind of boat it is, just that it floats and he got out on the water.

He probably wouldn't even care if the boat was bought.

There are all sorts of free plans for 1 or 2 or 3 sheet simple ply boats on the web, some can be slapped together in a few weekends.

It's easier to help someone to make a particular boat, with plans that can be shown, than it is to educate a person on the whole general scheme of boat building and how it's done.

 

I admit that I posted out of reaction to receiving the plans, opening them, and thinking about how lost I felt. I have since done a good bit of reading and feel I have somewhat of a grasp of how the plans flow from paper to build to boat.

I am constructing the jig over the last couple days. I had not worked with 'to scale' plans before, and I am used to specific dimensions being delineated for all aspects. I am about to assemble most of it. I do have a question about the stem. At the end of the ladder frame it is cut at an angle, and the frame(mostly 2x6) has a 2x4 that is affixed and fits flush to the stem. I am unsure how to ensure I have this is at the proper angle. It shows the stem is 78deg to the ladder frame. Any help would be appreciated. In case you're thinking, you should have paid more attention in geometry and trigonometry, I agree.

I am excited to get to leveling the ladder frame.
Tools necessary?
-Box plane?
-Shims? wooden or composite?
-Box level? 48"?

Again, thanks so much for the support.

 

For leveling long pieces, you can't beat a long length of clear tubing filled with colored water, the ends higher than the middle. Cheap and accurate

 

Once you have the ladder leveled, you can determine the angle by taking a measurement off of a vertical (plumb) post with an arm that is at 12 degs to complete the 90 deg from the ladder to the post. if you get my meaning.