Plywood Stitch and glue?

I am planing on building a plywood stitch and glue boat. I have an old 8.5 hp motor, for power, and want to have "row" be an option. There are a few plans I have, and the one I am thinking of is a 7'6" dingy/tender. I want to have a boat that is ~7feet, and able to be rowed and motored. I plan on the stitch and glue method, and plan on using this boat to fish, calm water, and hunt waterfowl. I don't have a truck, and want to be able to load this on my car, and want to keep it around 100 pounds. It should be flat bottom, and be able to hold 300-450 lbs, safely. If I can find a suitable "short" jon boat, that would be great, but, I think that a modified digny, with a 30% front end, and a flat stern transform, could allow me to meet my needs.

 

http://www.bateau.com/products.php?cat=9

 

Too much motor for the boat. Too heavy, too powerful. For 100 lbs you can build a 10 footer that will do what you want with some care. Try this: http://www.angelfire.com/ego/lewisboatworks/html/deslil10_a.htm ...on me! For an outboard motor to function properly...you will want some rake to the (rear) transom...optimal is about 15 degrees. Front transom and sides can be square.

Steve

 

Steve is right. 2 1/2 hp is about right for that boat. Why not build bigger? A 10 ft boat would row better and take the 8 1/2 hp motor (just). It will still weigh under 100 lbs.

Alan

 

Thanks, this is much help. A stitch and glue will support 8.5 hp motor, or do i need to go 1/4" for sides and botom, and 3/4" for the transforms?

 

Building method has nothing to do with power requirements. However, 1/4" is about the right ply thickness to produce a 100 lb 10 ft boat. To drive that boat with 8 1/2 hp, the expectation is that it will semi-plane, and therefore the transom will be wide rather than narrow.
There are many skiff designs that are perfect for your needs, and rather than design a boat for you I would suggest you look them over. In the ten to eleven foot range, a lot of great designs can be found cheap.
Remember this: what rows well will not plane, and the best rowing boats will use a tiny outboard. The 8 1/2 hp will allow faster speeds, but slower rowing.
The reason is the underbody shape, particularly in the back. A planing hull needs to ramp the boat up over the water using a wide wedge shape. Such a shape allows lift, whereapon the boat efficiently skims across the top of the water. Because a rower can't produce enough power to lift the boat, a boat meant to row well should be very efficient down in the water, where it displaces the same water at top speed as it does at rest.
A wide transom with a wedge-shaped underbody is a real drag to a rower. Since the shape is designed to be efficient with a lot more power than the measly 1/2 hp a human produces, such a hull is slow and hard to row.
In choosing to use a 8 1/2 hp motor, you are essentially saying you are not interested in doing much rowing. You will, however, probably get up to 12-15 mph.
All depends on what you are looking to do.

A.

 

Alan is right...but you already mentioned "jonboat" in your first post so I am assuming that the row option is much secondary to the power option. I hate to self promote but seeing as the plans are free to all...along with the LilJons there is Poorboy at 9+ to 11.5 ft or so which sounds perfect for your purposes and isn't even Stitch and glue, altho it could be made that way. It uses a simple chine log on straight cut sides, the bottom could even be traced out from the outline of the sides and transom and a mold in the middle. Using butt blocks you could build the hull in 1 day, finish it during the rest of the week and use it on the weekend. Check it out (below) as an option in your search for designs. Also check out the Boatbuilding Ring...excellent resource for plans and Ideas.

http://www.boatbuildingring.com/


Steve