To foil or fix

[kind_cir]

I have a 3.4m Allycraft fitted with a 9.9 Evinrude which is the max rated hp for this boat. It realy is just a bare boat fitted with a bimi top, floor and no other weight changes as such.
The trouble is it will not get up on the plane with just me in the boat. I do not want to fit a foil if I don't have to, so would raising the motor help the problem. Currently the cav plate sits 1in below the bottom of the boat.

[Kerry]

Fix! ??

Max HP? Then have no room to move there!

1" below? No harm done by lifting it an 1" to see what happens.

[gone_fishing]

im suprised it wont plan with one person are the allcraft that heavy i have a old 12' fibby with a mariner 9.9 it plans with a 150kg of poeple and gear it takes 3 poeple to carry
is the motor reving hard enough or maybe pitch of the prop is awol
a foil would help but not if your not comfortable
and the cav plate being 1" below is ok i think leave to the bottom is idea
all the best

[Blackened]

G'day

Whats the condition of the engine? Whats the condition of the prop?

Can you tell us what diametre and pitch of the prop is?

Try raising the engine another inch, so the cav. plate is level or just below the lowest part of the keel.

A 9.9 should plane a 11' boat with ease.

Dave

[tiny_tinny]

You could try adjusting the load distribution. In my 12 ft tinny, I built a shelf in the bows, made up a long fuel line and shifted the fuel tank forward. A fairly small weight, but it made the boat trim much better.

Mike

[kind_cir]

The motor seems to be in good nick for a 91 mod don't have a prob strating, idle or full noise. I do get full throttle as this is one of the first areas I checked.I susspect the prop is the orig and looks to be in good order no nicks or bends and a good shape.
If I put all me gear up front including a full fuel tank It will plane but takes a while and falls off the plane below 3/4 throttle.
With the 30kg, 7yo daughter up front it goes how I would like but falls off the plane below 3/4 again.
The hull is in good shape and there is no damage.
I don't want to add extra non removable gear as I put it on the camper trailer when I go camping.
My fat ass is 90kg on the back seat and I would realy like to move the 24l fuel tank behinde the back seat.
Do you think raising the motor would help or not?

[FNQCairns]

If there is no engine problem it's all most probably prop pitch, can your read what pitch is on it? Depending you may need to go down a couple of numbers, ATM the best it may be capable of is only 5hp (say) of the possible 9.9hp as thrust because it cannot spin the prop fast enough.

cheers fnq

[kind_cir]

If there is no engine problem it's all most probably prop pitch, can your read what pitch is on it? Depending you may need to go down a couple of numbers, ATM the best it may be capable of is only 5hp (say) of the possible 9.9hp as thrust because it cannot spin the prop fast enough.

cheers fnq

Can not see any numbers on the prop and it looks to be the right size & pitch but do not know for sure.

[kind_cir]

Just some more facts for ya to ponder. The top speed checked via hand held gps is 34kmh on the plane one up with all gear up front inc tank. The engine does not seem to be reving too hard nor labouring and there is no sign of cavitation even when doing circle work. So I assume the prop to be of correct size as I have not seen a smaller hp motor go this fast.

[Wayne_Red]

My brother had a 10' tinnie with a 15 on it. Plenty of grunt for that size boat. He put a set of fins on the motor and said it improved the boat out of site. Got on the plane much sooner, made it more stable going straight and in tight turn, especially one up. Best thing he ever did to it according to him.
Foils get bad press at times but it some situations they work well.
Regards Wayne