Need Help Outboard Mounting Height

[RRocket]

First, I'd like to say how grateful I feel to have found this forum! I am dealing with this from a position of ignorance; I've never had to adjust much of anything on any watercraft I've operated. So now that I have to, I'm totally clueless! I am hopeful some of the experts here can guide me to where I need to be since the local "experts" seem to know as little as I.

DETAILS: My boat is a Scout 365. The transom height from factory is 12". My Suzuki DF2.5hp has a transom top-to-cavitation plate distance of 17.5" despite being a short shaft. So that would put the cavitation plate 5.5" below the water, which is too deep per the outboard owners manual which calls for 0-1" below.

WHAT I DID: I asked for some advice from various locations and how to get a more appropriate depth. It would seem I'd need to make a riser. Which I did. A small issue with asking the local "experts" was whether the cavitation plate measurement should be from 0-1" below the TRANSOM or below the PONTOONS, which are the absolute bottom of the boat. Opinion was 50/50! So I went with BOTTOM OF PONTOON. 

RESULTS: The transom turned out well and looks OEM. See images. This puts the outboard cavitation plate .25-.375" below the pontoons. For further troubleshooting reference, this puts the same plate approximately 2" below the transom. So not a great deal of difference between bottom of transom and absolute bottom of boat/pontoons.

At up to 1/3 throttle, boat runs 8km/h. Beyond and at full throttle..no change. Bow rides high. Boat not planing. Not a sharp, beautiful wake behind boat. 

Now I understand this boat/motor combo isn't meant for speed. But similar boats with same power reach nearly 15km/h when they are planed out.

My question is...what now? I'm clueless how to proceed to "fix" this. Lower engine? Raise engine? Hydrofoil installed on cavitation plate? Go on a diet? LOL ? I'm 185lbs and realize having more weight forward is helpful. 

Any ideas?? 

 

Thanks so much for any insight!! 

[WIGuide]

A few things to try would be to make sure the engine is set to be trimmed down as far as possible as that will aid in any possibly of plaining. I'm not sure that small of an engine is going to be able to produce enough power to plane out though. If you can move any weight towards the front that will help as well and although I don't think engine height will be that critical, you could try moving the engine up higher to where the cavitation plate is about even with the bottom of the hull and see how that goes. 

[Fishingmickey]

Looks fine, cool set up!  Sounds like your under powered. Take your little son, daughter, niece or nephew someone who weighs less then a hundred pounds and see if they can get it up on plane.

FM