Help with designing outboard bracket

[Bartboat]

I really could use some help designing a new outboard bracket for my 23' self built power boat. I built the hull in high school metal shop out of steel 30+ years ago. We had it galvanized and have a merc 175 on it mount on a non flotation providing bracket and is used in saltwater with no problems other than being underpowered with old 2 stroke motor.
I just purchased twin merc 150 4 stokes and will need the new bracket to provide some flotation. It could be made from GRP or steel and then galvanized. I like to carry more fuel too. No aluminum or stainless.
Years ago the brackets looked much like the transom of the boat scalped down all around. Now there quite a few that look like they are quite free of the water on plane.
My goals are:
I would like to get as much flotation as possible. I envision the center area holding extra fuel sometimes. However, access to the engine mounting and the hull mounting bolts is getting a bit complex. Plus I need to have big access plates for the galvanizing to flow in there.

 

[DCockey]

Sounds like an interesting project.

What are your goals?

What does the boat look like?

Do you have a good estimate of what the boat with gear and passengers weighs as currently configured?

 

[Submarine Tom]

A simple hull extension makes senese. No fuel storage though, it's too far aft for that.

Pictures are needed before further comment can be made.

 

[Bartboat]

Hello David and Tom,
Thanks for the responses. Boat weighed in at 4300 but that was before a hardtop and some other stuff other stuff was added. Gear weight should be about normal for a boat it's size. We just hauled a 500lb wood stove, air compressor and 200lbs of groceries and some crap out to the place where we been building. The boat did fine even with the stove set so far back. We once had a 750lb tow behind wood chipper/shredder on board.
I'm thinking of only of added 25 gallons of fuel back in the new bracket. I posted a short video on youtube under bartdavis100 if you want to see an ugly boat. Bart

 

[tunnels]

Hello David and Tom,
Thanks for the responses. Boat weighed in at 4300 but that was before a hardtop and some other stuff other stuff was added. Gear weight should be about normal for a boat it's size. We just hauled a 500lb wood stove, air compressor and 200lbs of groceries and some crap out to the place where we been building. The boat did fine even with the stove set so far back. We once had a 750lb tow behind wood chipper/shredder on board.
I'm thinking of only of added 25 gallons of fuel back in the new bracket. I posted a short video on youtube under bartdavis100 if you want to see an ugly boat. Bart

Some of us cant get Youtube !! so pictures if possible . !!!

 

[Mr Efficiency]

This is her ? http://www.youtube.com/watch?v=Hynh2s50CtM&feature=plcp Can't see much, but looks to be a shallow vee hull.

 

[tunnels]

This is her ? http://www.youtube.com/watch?v=Hynh2s50CtM&feature=plcp Can't see much, but looks to be a shallow vee hull.

ike i said theres no youtube here in china !!

 

[Mr Efficiency]

ike i said theres no youtube here in china !!

If that link is the boat in question, there is bugger-all to see, last about 3 seconds and it is a long way away ! A shallow vee mono with a lot of cabin superstructure.

 

[Mr Efficiency]

This is the battleship in question ?

 

[Bartboat]

Mr Efficiency just pegged the classification type for this boat. We are all still laughing here. I will make a better video in a week and a half when I haul it back out and will show the transom. Sorry Tunnels, Don't know how to get pictures pasted here. Bart

 

[Submarine Tom]

Sounds like a hull extension motor pod would do the trick. You're going to be extending the lever arm on your outboards, don't add fuel weight to that as well.

 

[Bartboat]

Thanks Tom, are we calling the bracket a pod since it's enclosed? Is a transom extension the same too? Does anyone know where I could look for drawings for an aluminum twin pod version. I think with a little recalculation, I can make in steel?

 

[Submarine Tom]

Did you try Googling those key words?

All these names/words are just labels and mean different things to different people.

Pictures man, pictures...

 

[DCockey]

The current common usage in north america seems to be "bracket" for something which attaches to the transom and extends rearward with the outboard mounted on it and is not an extension of the hull, even if it has enclosed volume which provides floatation.

 

[Submarine Tom]

Pictures man, pictures...