Flooded Hull Boat ???

[Cane Pole]

This is a small 6/16 custom-built boat I have been working on for some time. I have enclosed the tunnel and left the back of the tunnel open so that when at anchor or low speeds the tunnel fills with water to give "free ballast". The boat is exceptionally stable. My question is where to mount the engine with respect to the bottom of the tunnel. At, present I have a lot of spray. This is a one of a kind type boat so I am on my own with the design.

Here is a picture of the tunnel which is enclosed about 2/3 of the hull length (covers the tunnel). You can click on the below pic if you want to look at more pictures. It has been a challenge.

I am open for ideas. I have posted this question several places.

[Barnacle Bill]

Did you ask on ScreamandFly.com? A lot of those guys are into racing tunnel boats and should have some good dope for you.

[CatFan]

What kind of spray? From the LU or the prop or somewhere else?

Kind of hard to judge angles, but it looks to me like your prop shaft is going to be fairly shallow when you trim down. How fast does the boat go, and at what speed do you get the spray?

[Cane Pole]

What kind of spray? From the LU or the prop or somewhere else?

Kind of hard to judge angles, but it looks to me like your prop shaft is going to be fairly shallow when you trim down. How fast does the boat go, and at what speed do you get the spray?

Looks like a plow breaking ground at high speed. I can't see good when driving. Boat goes about 25mph. The anti-cavitation plate is about 2 inches below the bottom of the boat.

["G"]

Raise your motor up.....put the cav plate even with the bottom of the boat is what I am thinking......worth a try anyway. I think it should be even with your trim tabs on the boat.

[Rees Guide]

Raise the plate up even and try it Cane, the plate may be causing the spray.

[CatFan]

Looks like a plow breaking ground at high speed. I can't see good when driving. Boat goes about 25mph. The anti-cavitation plate is about 2 inches below the bottom of the boat.

You want that cav plate closer to the top of the water. You may have to invest in a manual jackplate to dial in the position.

[Rees Guide]

Raise your motor up.....put the cav plate even with the bottom of the boat is what I am thinking......worth a try anyway. I think it should be even with your trim tabs on the boat.

Think we were typing at the same time, seems to be an echo in here!@!!!

[Barnacle Bill]

Tunnel boats were designed for operating in skinny waters. Normally a jet drive would be installed on a tunnel boat and the motor, regardless of drive, would be mounted higher than normal to take advantage of the tunnel. But since Tom apparently blocked off the front of the tunnel and it is drastically affecting water flow when moving. I've never heard of anyone doing that mod to a tunnel but then there are a lot of things I have never heard of. Or just plain forgot. Interesting tho.

[Cane Pole]

I believe Swift boat makes one. Can't remember. They are out there but not in numbers.

Google Image Result for http://www.boatdesign.net/forums/attachments/boat-design/11397d1170460016-flooding-hull-fjordling_17_006.jpg