Stabilizing a big freighter canoe

[Bing]

I'm hoping you'all might give me some direction. I want to fit amas to a
fibergalss Scott 21 ft Hudson Bay outboard powered freighter canoe. The HB21 is 4ft 8 in wide, and with an 8hp 4 stroke and light load will do 12 to 15 mph on a smooth river or lake (fully loaded maybe 5 to 8 mph). The boat's people and cargo capacity is around 2000 lbs. It's used primarily for ferrying clients and their gear to primitive camps in the north country, or for cruising rivers and large lakes. This is not an ocean going boat, and is limited to bad weather conditions of 20 to 25 mph winds with up to 1.5 ft lake type whitecaps. She'll handle worse, but sometimes the best bet is to lay low.

The point of adding the amas, or outriggers (not sure of the proper term), is to increase the stability of the boat. I want to have passengers (say up to four) sit on platforms over the gunwales without worrying about how many butts are on one side or the other, thus leaving a little more leg room around their gear stowed on the bottom, and fewer coffee spills. One might consider a wider boat, but that long lean hull doesn't take much horsepower to move (or fuel...and is quiet) is very shallow drafted, and weighs 250 pounds dry. Hard to beat for the purpose.

When anchored, it would be great to be able to spread out and take a nap on the outrigger platforms. That requirement suggests a 250 lb person sleeping on a platform 45in wide x 78in long, with one edge of the platform attached to the gunwale, the other over the outrigger, without the boat listing excessively (some cargo shifting might be required in order to effect perfectly evel trim, and that would be more or less OK).

I wouldn't want the amas to seriously slow the boat, nor make steering more difficult. The outriggers need to be rugged, but light, and capable of folding or telescoping, or being dismounted, when trailering. When underway, I don't think a wide beam would be a problem, but it might be nice to keep that to the width of the boat, plus 4ft either side, to say around 12 to 13 feet. Because the boat heads out fully loaded, and returns empty, the draft might vary about 4 inches (I threw that info in thinking that the amas may need to be adjusted for varrying boat drafts).

So, do you think this is all a bad idea? Am I in for dissapointing performance? If the idea has merit, here's other questions:

1. What size (displacement-length) amas would I need?
2. Does anyone make suitable amas and crossbeams that could be readily fitted to the canoe? I'd prefer not to have to build these myself, wanting to use a tried and true design if available. There may be other freighter canoe owners who'd like to do the same thing, if all this works out.

That's it. Thanks for any suggestions and recommendations you may have.


Bing

[FAST FRED]

I'd prefer not to have to build these myself, wanting to use a tried and true design if available.

Go to the good folks that sell aluminum pipe and build a lashup as a test..

The displacement of the amas WILL cost some speed , or require more effort paddeling to drag them thru the water.

Try about 10 -12 inches in diameter , and see how it goes.

FAST FRED.

There aint no free lunch.

[garydierking]

What you're trying to do is also the most common way to rig a canoe in the Philipines. Have a look at:
http://www.angelfire.com/ex/ti/FilCanoe.html
I also have an ama building tutorial on my site.
http://gary.dierking.net

Gary

[Bing]

Thanks for the tips and info. I ran across a website (www.jpwinc.com) of a company the specializes in inflatable river raft pontoons. I think that I will pursue this option, as the pontoons are obviously very strong for bumping up against things, deflatable for trailering, and very light weight.

Any other tips or suggestions out there?

Bing

[frosh]

You may be familiar with Easyrider kayaks and canoes. They seem extremely well designed and manufactured. They do outriggers and poles to mount the outriggers to the main hull. Rigid, so no folding or collapsing of the outrigger pods themselves, but seem easy to disassemble. See this link: http://www.easyriderkayaks.com/outriggers-c.htm

[Chris Ostlind]

Hi Bing,

Jack makes really great products, but the smallest diameter, standard tube you can get from him is 12" at a ten foot length. You can have Jack build smaller diameter tubes for you as a custom order and at a premium price. He's one of the best guys in the business to deal with for stuff like this. He tells it like it is and delivers exactly what he says he will.

Standard 12" tubes would work for you, but I would bet that your boat has less freeboard, when loaded, than 12". If you can raise the mounting points for the cross beams/tubes you may be using to attach the floats so that they provide at least 12" of water clearance when the boat is loaded, then you can buy Jack's standard tubes and get on with it.

I have used inflatables on my sailing canoes for many years now and there are several solutions to what you want to do. Some are better than others for simplicity and durability.

Chris

[Bing]

Many thanks for the input. It will take some time to pull this thing off, but I will get back with everyone and let you know how things worked out. Can't wait to get started with all the suggestions and leads you sent.

Bing