Boat building questions

[Jeff Johnson]

Been hanging around this site off and on for a couple years now, and have picked up a lot of good information about one of my favorite pastimes, as well as just really enjoyed it for the entertainment value.

Thinking that it is about time for me to take the plunge and build a serious duck hunting boat. I really like the looks of the BBIII. I have built a couple of small, simple plywood and glue boats, and I'm not a complete novice at wood working, but I have never tackled anything quite this large. Currently reading Sam Devlin's book, and getting psyched up. Hopefully the folks here will be able to help me along.

Have a couple of questions right off. First, in many of the photos of the BB boats that I see here, it appears they have long shaft outboards and the motor mount has been raised well above the rear deck height. I'm wondering why you wouldn't just use a short shaft motor and not have to build the transom way up. Seems like this would also make the transom a little bit stouter. I also think it makes for a more compact and easily concealable look with the motor down lower. Is this just because the boat was built to accommodate a motor that the builder already had, or is there some reason this is necessary?

Second, I notice that some boats have all manner of stuff attached to them. Lots of it looks like it requires screw holes or holes drilled thru the wood. How do you keep moisture out of these many openings in the skin of the boat? I have had lots of boats with holes drilled into them or things screwed on, and it seems like you invariably get some water in there. That can't be good on a wood boat.

 

[Pete McMiller]

Jeff,

I only know of one BB that has/had a long shaft motor and that was Lee Harker's BB2. All the other BB3's I have seen are sporting a short shaft motor, mine included. Go with a short shaft if you can for all the reasons you indicated.

Yes, we drill holes thru the wood for all manner of stuff from cleats to blinds, grass rails, etc. Typically when you drill thru the wood you would then coat the inside of the hole with epoxy before putting the screw in, just to seal it up. I also bed everything in 5200 to make an even better seal. So far in 7 years I haven't noticed any delamination or other signs of water.

 

[Ray]

My BBIII sports either a short shaft outboard or a small long tail. I do use a mechanical lift to allow for shallower slow running depending on water conditions. It does effect performance compared to when the outboard was just on the transom: Lost top end speed, and started cavitation in turns.

One of the things that is important to the perfomance of a BBIII is to have the motor mounted at a height that matches the individual outboards "best" performance height. Typically this height is related to the distance below the hull that the cavitation plate is set. This distance varies a little between each motor. I think my Nissan 25HP had a longer/taller height than what was called for in the plans so my transom height is about 1.5 inches taller than the plan height.

In todays market you are seeing people with four stroke motors on their boats. Those motor heads are typically taller than a two stroke. With the shaft length the same, these newer motors will stand taller over the deck. If you build it to be lower, you may have an issue with rough water coming over the stern, and porpoising at planing speed. These sneak boats are not just marsh boats, they are designed to be used in rough weather. If you make your transom too low you will swamp the boat with a following sea. The design for the BBIII does not include a self bailing transome, but you could build one of your own. You will have to consider the design and performance issues that could occur.

I take it you have built some Hybrids following Rich's plans. Good little boats that are simple to build. I have been an advocate of them for years now, but I recommend a stitch and clue construction rather than a sheet glued on frame.

For sealing hardware we use 3M 5200. It will be called out in the plan list of materials. It comes in black or white. The white also comes in a fast cure formula. When I built my BBIII I used about half a small tube for all the hardware originally mounted on the boat. Since then I have used two half tubes for additional hardware and sealing holes from stuff I removed.

For hardware that will be through bolted one technique is to drill a larger hole, fill it with thickened epoxy, and once cured drill the correct size hole for the bolt then seal that hardware with 5200 or another marine rated sealant. For screws I pre drill the hole, fill with 5200, then make sure the contact surface of the hardware has a thin layer of 5200 and mount it up and make sure there is squeeze out, but do not over tighten the screws. 5200 is a fairly roubust adhesive once cured so you don't need to crank on the screws.

The secret to not letting water in is maintenance. Build it correctly with the correct materials, and then keep up the yearly maintenance and a wood cored boat will last a long time. Every year, or even during the season, you need to check for dings and dents and paint them over or fill them if they get down to the wood. Its a never ending process.