Bow shape for small tri

[GTO]

I'm planning on building a small simple trimaran with vertical sides and flat bottom - sharpie style.
The intended waters would be mainly lake use but also just outside surf zones along the Florida gulf coast in decent weather.

I was wondering what effect a square, swept up bow (ie, bottom of hull comes up nearly to deck level) would have as opposed to the more common pointed bow.

I'm considering a main hull of 16', beam of 3', sides 18", square transom slightly swept up to clear the wake.

Any opinions?

[duluthboats]

Sail or power, if power, how big?

[GTO]

Boy, I feel dumb.
That would be sail. Most likely sloop rigged.
I plan to try an A-frame mast first.
What prompted my question is a concern about slamming. Not a problem on the lake really, but wondered about the gulf coast.

[diwebb]

Hi,
the type of bow you describe is not very efficient, it shortens the waterline length and hence the displacement speed, and the bow slams in to every little wavelet probably stopping any chance of planing. I would reccommend a pointed bow every time for this type of boat.
James Wharram used flat bottom and almost vertical sided hulls on some of his early catamaran designs, you may want to have a look at these for some pointers.
A three foot beam for the central hull seems a bit wide for a sixteen foor trimaran. Most multihulls in this size bracket are much narrower in the water to get a good slenderness ratio for good speed potential. A V hull with a small amount of flat on the bottom at the center tapering to a pure V at the bow, somewhat like a very narrow dory, may be a better bet.
All the best with the project.
David

[Fanie]

I have built me a small tri a while back. It's 5.5m. I should have made it 8m instead, for all the reasons.

[GTO]

Thanks for the information.

I'm building more of a sailing dinghy with training hulls, since I'm trying to get my wife interested in, and enjoying, sailing. She doesn't like the heeling associated with my unballasted sharpie. I also want the boat to have some load carrying capacity, while maintaining a very shallow draft (4" - 6"). I've not determined the maximum needed displacement yet, but the beam will likely get narrower as I figure that out.

I'll ditch the flat bow idea. My sharpie slams enough with its flat bottom, I wouldn't want anything worse.

Thanks for the responses.

[Fanie]

If you want the wife interested, it better provide her a dry ride - trust me.

[GOTTABSOMEWHERE]

Hey "gto"

Do You Have Plans For The "a" Frame Rigging ?
I"m Looking For Same
Pls Respon
Thanksd

[GTO]

No, I don't have any plans. I've made 5 masts now for my 16 foot sharpie, so I believe I can come up with a working A-Frame mast. Not saying it will be the best, but at least "working".
I might end up making 5 A-frames, but since I will just be laminating pine or spruce planks, its not really hard or expensive to do.