alls good

[CaptDan]

Extreme Flats 20 not false:

but thanks anyway

[Cracker Larry]

ANY SUGGESTIONS ?

First off, you will need more HP to go much faster than you are. That's a big boat and 40 hp isn't much.

As to the flooding, never heard of such, that ain't right for sure. It has to be a serious trim issue. Can you post pictures of your transom and engine set up? If you don't know how, email them to me. LTeuton at aol dot com

My other thought maybe possible about the flooding, does the transom and bottom joint meet in a round edge or a good sharp one?

[TomW1]

I'm like Larry very puzzled. First for that boat and motor combination you need to go down to an 11" or 9" pitch on a four blade prop. And or up in HP and propeller size. Give me your tach readings at full speed, with the 13" pitch and I can be more specific.

How is the trim of the boat? Is it trim down at the stern? That could be causing the water to be coming off the bottom and up into the boat.

Larry had a good point are the rear surfaces where the water is leaving the boat fairly sharp. They need to be sharp enough just so paint will hold on say a 1/16".

[Woods Designs]

You will need to know the WOT revs before you can decide on which is the best prop to use. If your boat doesn't have a tach then you can get the digital wrap round spark plugs ones very cheaply on ebay or Amazon. They do work well. Let us know the revs you get, the max revs you should get and we can advise as to the best prop. Once you have sorted the trim problems of course. No real point in tuning the engine before the boat, but it does sound as though you are running in a semi displacement mode

Richard Woods of Woods Designs

[jacquesmm]

It's premature to discuss the details of the prop.
As Richard writes

No real point in tuning the engine before the boat, but it does sound as though you are running in a semi displacement mode

With hundreds of XF20's afloat, all running well with different size engines, we never heard of that water throwing phenomena.
Where does that water come from? Over the bow, the transom? The sides?
You may be at a ugly trim pushing a big wave at semi-displacement speed.

I also agree with Larry: with 40 HP, a boat with the sole option and at least 2 persons onboard, you are at the limit of the required HP.
The max. 50 HP is for the standard version: light, no sole. I have been on one of the first ones with a 25 but light and tiller version and it performed well.
Most of the sole option ones use a 75 and some go higher: see the study plans picture with a 115.

Bottom line: you are somewhat under powered for a fully fitted boat with a crew of 2 or more. I would try to swap that engine for a larger one before fiddling with the prop and engine height.

PS: I saw that you emailed before and tested the boat with Billy Henderson. He is building boats in the same style and I don't think he is a supporter of my design . . .

[CaptDan]

Done

[Aripeka Angler]

Hi Dan,
Sorry to hear that you are having an issue with your XF20.
Can you post a photo of your setup? Is the distance from the top of your transom to the top of your tunnel 16" or 20"?
My guess is that the fixed part of your jacplate is too low and is deflecting water over your transom.

[CaptDan]

I just posted pictures of the transom with Jack Plate and Water Flooding over the transom in front of the Motor.

[pee wee]

[jacquesmm]

When I wrote trim, I was thinking about hull trim, weight distribution, not engine trim.
I'll try to find your pictures tomorrow: I am at home and have a slow connection.