Lifting Strake Construction

Yellow Jacket - I am completely unfamilar with the Dingo Tweedies excel spreadsheet that you referenced and also am not sure how to go about calculating edge turndowns. Please provide for information.

 

I apologize, I posted in a hurry and didn't reread what I typed. What I intended to suggest was plywood, epoxy and fiberglass could be used, high density foam would be a plus but there was no need for plugs.
I believe that counter sinking plywood deep enough for plugs is not a good idea.

 

Here is a link to the spreadsheet.

http://www.boatdesign.net/forums/design-software/savitsky-power-prediction-2187-6.html

So far as I know there isn't a way to calculate or predict the edge effects or a canned way of designing the chines that you are doing, I would suggest that you look at hulls that are claiming low speed efficiency improvements and copy those.

 

I'd agree it may be beneficial to use some sort of edge or fence treatment, but where, how big, type, etc. I wouldn't want to hazard a guess.

I do believe if the after half of each hull is squared off, there will be enough plane surface. Then the question will be; is there enough power. A buddy with a 22' fully dressed pontoon boat does moderately well with a 90 HP Honda, but at half the weigh of this boat. Using the same multiplier and doubling the weight I get 14.5 knots (17 MPH) which is up on plane a scooting along at over S/L 3.1. Not exciting, but respectable and you will not make a career out of crossing a lake.

 

Thanks for your assistance guys.

I read your original version with the same meaning as your revised message. We must be of the same mind set.

I am going to attempt to square off the after hulls as suggested. I do expect to have the strakes put her over 20 MPH. I was clocked by a friend at just under 19. At that time, my rebuilt motor had only about 2 hours on it, there were 4 adults on board and the trim pistons were not holding the engine at all. The flattened tail should help.

Yellow Jacket - Thanks for the link.

 

If you were "clocked" at 19 (MPH?) you where up on plane. I wouldn't trust "being clocked" just too much to toss off a good reading. Install a speedo or use a GPS.