high speed hull

I'm in the planning stage of building my next boat. I have a marinized 150 hp Mazda 13b rotory engine and would like to know what hull would be best for high speed. I already have a 3 point hydro and that style is still doable. I can get plans for a step hydro called the flyer 15 altho I like the stern design of the Stancraft Torpedo better. I don't plan on racing this. I like speed with the wow factor.

 

A lot more information needed. You must post a statement of requirements (SOR) before you can get a considered answer.

How fast do you want to go with your 150HP rotary?
How many passengers must the boat accomodate?
Will the boat encounter rough water at high speed ?
Is comfort a factor?
Will you be building the boat or will you turn the job over to an exprerienced professional builder.
Do you have a particular material that you intend to use...FRP, wood, aluminum?

 

I live on a large lake that has no speed limit. The boat will be built by me out of wood. (This won't be my first project) Seating for one, maybe two in front or behind the engine. The lake gets rough at times, but that is when my high speed boats stay docked. As for speed, the engine can do 9000 and I plan on no transmission with a 1 to 1 drive. I like the looks of the

 

Flyer 15, a boat tailed steped hydro of the 40's, with a transom like the Stancraft Torpedo 29.

 

If you want to ride in rough weather, you might be better of not to use the stepped hull form, cause of the slamming that may occour. Perhaps you have some picture of a desired design to share in this thread?

 

If you need to outrun redneck bass boats you are going to need something capable of well beyond 70 MPH. The vintage boat tailed boat will not be a best choice in that case. Something more on the order of a pickle fork might do it with the 150 HP engine.

I suggest that you get Dave Gerrs Propellor Handbook ISBN 0-07-138176-7 before you select a boat design. You are dealing with an engine (Wankel I presume) that likes a lot of revs. If you must direct drive the prop, then you will need to do some research into the shaft and prop system you can use to best advantage. You might be looking at a surface drive system. Wrap the boat around the system that best utilizes the components. That narrows the boat selection process some. In any case the boat must be ultra light when speed is the goal. Every pound matters.

Use the search function and find threads where Jimboat participated. He is the resident authority on all this.

 

I used the Castle Marine prop calculator and a fast runabout hull weighing in at around 800 lbs and spinning a 9x16 prop at 6000 rpm will get me (on paper that is) 84 mph. This is going to be my winter project anyway. My next boat will have a 32 hp jetski engine with a prop on a rigger hull.

 

Grand Prix 2012 Redbull Winners VanDutch over Hull

Grand Prix 2012 Redbull Winners VanDutch corner