Canadian small boat construction regs

[Paul Moir]

I've been playing around with a light plywood runabout design for a while, but I've been stuck on a regulation. If the deadrise is less than 5°, you follow one equation for maximum recomended horsepower, and if you exceed 5°, you follow another. Since the 'less than 5°' equation doesn't account for remote steering, there's a large difference. Maximum goes from 20hp to 40hp on my virtual runabout. It needs to be 28hp <br /><br />Here's how they put it:<br />

Midship deadrise angle greater than 5º, (No Flat bottom Boats), ...

My questions are:<br />1) I've found 'Midships' mentioned in the regs as being a section precisely halfway between the tip of the bow and the top lip of the cutout. What is the significance of deadrise here? I thought it was only important on the running surface? Currently my bottom only has 3° here, but I could increase it easily enough.<br /><br />2) Do you think the '(No Flat bottom Boats)' basically rules out what I'm implying to do in 1)? I mean, it's flat at the back afterall.<br /><br />3) Say I change the bottom from flat to 5° all the way along until the back. How will that alter the ride? Will it slow me right down?<br /><br />Unfortunetly, there's no consideration for anti-trip chines and the like. Of course, this is a protected waters boat.<br /><br />I'd really appreciate hearing your opinions. I can post the lines if you want.

 

[mellowyellow]

Re: Canadian small boat construction regs

ask these guys: http://www.ccg-gcc.gc.ca/main_e.htm

 

[JasonJ]

Re: Canadian small boat construction regs

I am of the opinion that you should run 5 degrees all the way back anyway. You'll get a better ride, it will be safer in turns, and five degrees is shallow enough to not need a ton of power. Typically, the more deadrise you have, the more power it takes to get on and maintain plane, but 5 degrees is pretty shallow so you would end up with a decent compromise.

 

[Paul Moir]

Re: Canadian small boat construction regs

MellowYellow - I guess you already know the CCG publishes the regulations I'm talking about. It's not a bad idea, except I doubt I could ever get a reliable answer from the bureaucracy there. Sort of like asking the DA to interpret the law for you. <br />Still, I'd get some sort of opinion out of them. <br /><br />Thanks JasonJ - I should have mentioned the original design calls for a vertical fin forward protruding from the keel to aid steering. Sort of something you can pivot on. I never thought about it, but I guess if I go to a vee I could leave that out completely. <br />That would sure simplify things.<br /><br />I looked up JB's theoretical maximum speed formula, and it appears I'd only loose about 10% in that department. I was really only worried about it's ability to get up on plane. Thank's for the reassurance!

 

[Paul Moir]

Re: Canadian small boat construction regs

One bump to see if there's any more opinions left out there! Otherwise it's not going to be flat bottomed!

 

[Hooty]

Re: Canadian small boat construction regs

I'd put tha 28hp. on it and if there's b/s, I'd explain that's the way I interpreted the rules. Nobody's gonna question it.<br /><br />c/6<br />Hooty

 

[Paul Moir]

Re: Canadian small boat construction regs

Thanks for the reply Hooty. I guess I should have wrote above that the reason I'm even bothering with a capacity plate is so that I can get a license for the boat. The boat's engine is over 7.5KW (10hp) so I need one.<br /><br />I've got to send the Coast Guard pictures of the boat and various measurements (and money) and then they issue me a capacity plate. One picture must be of the transom. They may decide it's flatbottomed at that point, and give me a low rating. I'm starting to think that mellowyellow's idea is the best, seeing that I'm really at their mercy. I'll just have to hope they don't change their minds between when I ask and when I apply.