Outboard mounting height

[hunter armytage]

I have had it sugested that the 30 Hp outboard I run on my 4.1m tinny is mounted too low.

Has anyone got any opinions on what height my cavitation plate should be mounted in relation to the bottom of the hull?

[shortie]

Thats depend on your hull.

The normal is equal with the bottome of the hull.

However some hull designs disturb the water to much at that height and can cause cavitation.

SO i would start equal with the bottom them move up or down depending on the performance you get.

[Smiderman]

Yeah I'm with shortie the bottom of the cavitation plate should line up with the bottom plaining surface of the boat

[mick fillet]

just keep lifting the out board one hole at a time till the prop cavitates then drop it back down to the previous hole. you get more top end speed by lifting it a hole.

Its good to see that your trying to get the most performace out of your rig by mucking around with it.

mick

[shortie]

mick fillet wrote:

just keep lifting the out board one hole at a time till the prop cavitates then drop it back down to the previous hole. you get more top end speed by lifting it a hole.

Its good to see that your trying to get the most performace out of your rig by mucking around with it.

mick

Also remember that when turning if it is 2 high it will also break the surface of the water.

[upwindoverdrive]

If when you start toward planning the bow skies and appears to be hard to get over the "hump" then your motor is too low. I raised by 25 Four stroke up one hole from how it was supplied and now have little to no "hump" to planning, better top end speed and far better "hole shot". The extra weight of four strokes do drop your hull slightly lower into the water then what you would expect level with the bottom of the boat.

This advise came from Steve at SOLAS up the coast. Very helpful guy - recommend his service.

[Malcolm]

upwindoverdrive wrote:

If when you start toward planning the bow skies and appears to be hard to get over the "hump" then your motor is too low. I raised by 25 Four stroke up one hole from how it was supplied and now have little to no "hump" to planning, better top end speed and far better "hole shot". The extra weight of four strokes do drop your hull slightly lower into the water then what you would expect level with the bottom of the boat.

This advise came from Steve at SOLAS up the coast. Very helpful guy - recommend his service.

this is what happened to mine and i put weight in the front but maybee i should raise the motor ?

ps it's bouncy as untill i went flat out then it was good

pps its good now with the weight

[hunter armytage]

Thanks guys appreciate the help