Bracket mock up

jasoncooperpcola · #1 07-12-2012, 09:23 PM

I cut some cardboard into the shape of what my bracket should end up. Its rather large.

Its 41" wide, 17" tall, and has a setback of 30". Totally submerged it will provide about 850lbs of floatation. Assuming my waterline stays the same, about 10" will be submerged. So that is about 550lbs of floatation.

First pic, the sharpie lines are where the outside of the stringers are. My plan is to extend the stringers out the transom and build my floatation box off the extended stringers.

This is the basic bracket shape. I cut it too tall, so i just dropped it below the hull for now. Ran out of light and i will cut it correctly tomorrow. That is a 2' level on the top for reference to size.

What do yall think? The outside edges of the bracket will be flush with the bottom of the hull at the strakes, and the bottom of the bracket will be flat. I will have 5" between the bottom of the boat and the bracket.

I think its the best compromise for the most floatation and also keeping the basic purpose of a bracket. RidgeRunner linked a site, http://www.hermco.net/ thier design has the most floatation, but i believe their design does take away some of the performance aspects of a bracket as they dont "swoop" up any.

cterrebonne · #2 07-12-2012, 10:38 PM

Looks like you will have a lot of flotation. How close to the bottom of the boat will the bottom of the bracket be?

jasoncooperpcola · #3 07-12-2012, 11:11 PM

Should be 5". Badnews. We just got a rain storm and my bracket fell apart, i guess i need more duck tape.

macojoe · #4 07-13-2012, 05:37 AM

being that i converted my v to a bracket, i would shorten the set back to just what you need to tilt motor. You really don't need to lift motor up all the way up. further back adds more leverage on transom and changes the center of gravity quite a bit. I always wished i went shorter with mine, but i bought a used Armstrong and beggars can't be to picky! But are building so you can do what you want. but looks good from here!!

spareparts · #5 07-13-2012, 06:34 AM

I'd agree with MJ, make it shorter. I'd also make it taller, the biggest mistake in converting a boat to a bracket is mounting the motor too low. You also need to make sure you have a clean break(step) with the hull bottom. If you don't it acts like extending the hull length, which will add a lot of drag

RidgeRunner · #6 07-13-2012, 07:08 AM

The "clean break" area on my Stainless Marine bracket and the swoop are the precise areas where Hermco fills the gap.(Big Shrimpin's brackets too) By closing in a little more of that void on the underside of the bracket, they add floatation.
I don't think they go so far as to hurt the performance. Water rises as it leaves the rear of the hull but I watch where the water hits the lower and I know there is more room to add some additional floatation below the waterline. I was thinking of starting at 1.5" from the bottom at the transom with a swoop that winds up approx 2 to 3" higher than where I have noted the water hitting the lower unit. (Now there is 6" to 7" from the bottom of the bracket at the rear to the waterline on the lower) If it was 4'wide that would be a couple extra square feet of floatation at rest and yet completely out of the water on plane AND being 4' wide the boat would certainly be more resistant to transom sinkage when there are four people standing at the transom. LOL.. It would need to be light enough to reap the benefits yet strong enough to withstand the beating of a barely used 300XS Merc.

Umm , did I stray?

cterrebonne · #7 07-13-2012, 09:01 AM

I thought that the bracket being longer than mounting the engine on the transom helped the boat ride better in seas?

RidgeRunner · #8 07-13-2012, 09:04 AM

Quote:

Originally Posted by cterrebonne

I thought that the bracket being longer than mounting the engine on the transom helped the boat ride better in seas?

I have heard the opposite. I can't tell any detriment but I never rode in it before the bracket was installed.

cterrebonne · #9 07-13-2012, 09:17 AM

Quote:

Originally Posted by RidgeRunner

I have heard the opposite. I can't tell any detriment but I never rode in it before the bracket was installed.

I guess there is a point of diminishing returns.

macojoe · #10 07-13-2012, 09:27 AM

longer makes it harder to steer i think. reverse is tuff to steer even on the sea ox, also when adding bracket you need to add a inch in height for every 6" of leanth. and as stated above a bracket should be at least for a 25" motor! shorter and it will get wet from following seas, some times getting swamped!