Walk, not saw

August 23, 2007

Not much boat work last night. I took my exercise hour and went for a long walk and think rather than playing with wood.

I then went home and measured the bottom for the model, but decided I was too tired to do any cutting.

Some more thoughts on materials below the fold.

I am using a few rules of thumb on materials.

If I have to justify using it, it may not be a good choice. Think again. (It might be the best choice, but think again first.)

Go cheap or go quality, but don't mix and max (Michalak interprets Bolger)

The boat should be built to suit its purpose.

The purpose of the boat is to be:

Easy launching / cartopping exercise boat.
That is safe.
That can carry boys.

The priorities here are weight first, then strength, but don't go for low weight at the cost of strength.

It also means that the boat is gonna get banged up - dropped while loading, hauled up on concrete, etc. I have to assume that any coating is going to get damaged.

So, marine plywood to slow the progress of rot once the boat gets scratched. Weight tells me to go with 3mm Okoune at about 13 lbs/sheet. (5mm Oukune and 3mm Meranti are both about 20 lbs/sheet) Strength tells me to take some of my saved weight and use it for grounding runners on the bottom of the boat. This will also help with bottom strength.

Plywood will probably come from South Jersey Lumbermans - speaking of which I need to call them and check prices.

Strength tells me that the grounding runners and rub rails need to be strong wood - oak or ash. I expect to rip these down from Lowes boards unless I find a better source.

Consistency in materials tells me to make my bulkhead frames out of the same material, not out of soft easy pine. Bother. Looks like I get another workout.

The skeg is going to be mounted outside the fiberglass. Ash if I can get it, pine otherwise.

I will need 4 sheets of ply for the boat, a 5th for the decking. The decks could probably be made with big box Luaun underlayment. My decision will hinge on the price of thin wood. I am resisting the idea of making decks and transom out of Meranti and leaving them bright. But they are small pieces, and it might make a big difference in looks.

Speaking of looks, I am going to do some bathtub tests on the models before I decide if I will want square or round access hatches to the decked areas. Round screw-in hatches are pretty watertight, and that is the way I am leaning. Overbuilding here, but see the line about justifications. If I get swamped, I want those hatches to stay ON!

The bathtub tests will let me decide if the hatches can go in the bulkheads or if they will have to go on the decks. Square hatches do look better on deck tops. Ah, the fun of agonizing over details.

Looking ahead at the construction, the one thing that is bothering me is planing the transom frames, wales, and skeg. I don't have a proper workbench. I may have blogged this before.

And back to work.

Posted by Red Ted at August 23, 2007 10:23 AM | TrackBack