Help: info needed for Avon Typhoon S4.00

[russhenchman]

Hello everyone!

I could use some help. I recently bought an 1990 Avon S4.00 Typhoon. The boat is awesome except for a handling problem I am having. Once on plane, at certain speeds the boats wants to occasionally hop out of the water almost as if it hit a speed bump even on flat water. It almost feels as if the bottom fabric is stretched not letting the water flow smoothly underneath. Although it feels tight if I bounce my hand off of it. I have tried every combination of air pressure and weight distribution.

Questions:
1) Should this boat have a thrust board? I see that some models do and others do not.

2) If the bottom is stretched out, is there any way to tighten it?

3) Where could I find the optional side helm and inflatable seat? IBS does not carry them any longer.

4) Should the keel be glued down at the fore and aft ends?

Any other information or tips about this boat would be greatly appreciated!

Thanks guys!

[Downhilldai]

Lovely SIB

Is the keel chamber inflated?

[russhenchman]

Thank you Downhilldai!

Yes the keel is inflated. I have tried different pressures from 2-4 psi in the keel.

[mister p]

Keel chamber should be fixed about the centre but free fore and aft. When inflated it's held in place by it's pressure against the underside of the floor and the hull.

[mister p]

Engine might need trimming in a touch. Could be light porpoising.
Cool boat though. Try it without the fins.

[Downhilldai]

Originally Posted by mister p

Try it without the fins.

Was about to suggest this

[mister p]

Yes, on that set-up from your pictures can't see that the fins would be first on my shopping list.
Trim in, ditch the fins. But do these one at a time as you won't see the benefits clearly.
Trim in first, then if no good, trim back to where you were and lose the fins. Then after that try the trim again.
But as I said, your rig looks cool so it shouldn't be an unfixable issue.
Nice one Dai.great minds think alike

[mister p]

Or at least yours does!

[mister p]

Having had a closer look at your picture of the rear of the boat, I'd trim in one notch first.

[russhenchman]

Thank you for your help Mister P. I have tried every pin position on engine bracket. The lower the position the worse it is. I will try without the fins next. They came with package but I don't know if I've ever seen another SIB with them!
When the problem happens, it feels like a bulge of water is being formed underneath and then the boat hops over it. The boat even jumps to the side a little.
Anyone know if this boat should have a thrust board?