Re: cavitation height?
at planning speed the cavitation plate must never have water over the top of it.
when running at max speed get the engine up as high as possible ,but make sure you still have plenty of
water getting over the intakes on the side of gearbox.
if the cav plate is on the water its causing drag and the plate is trying to lift the boat,THIS IS WRONG, the plate should be
just skimming the surface not being used to lift it.
when people put on doel fins they think the fin should ride on the water !!! this again is wrong,it puts pressure on the plate.
the fins are only designed and meant to AID in getting it up.
if your engine bracket has the bia bolt patter )fitted to nearly every engine 40hp and above), then try it on the holes so the
engine is up the highest.
if this gives plenty of water and dont cavitate bad in the turns then this is better for your boat/set up.
But also you can buy different props that will work best at different height !!!!!!!!!
this is extreme but is very true with what ive got for my 60hp rude triple.
12 3/4 x 23 pitch alloy this prop likes to run deep down with engine on its lowest setting (cav plate 1 inch under the boat)
13x 19 stainless prop, this one likes to be with cav plate 2 to 3 inches above bottom of boat.
13 3/4 x 23 stainless semi-cleaver, this prop will only work correctly when the engine is way up and the centre of the bullet
on the gearbox 1 inch below cav plate ( thats cav plate 5 inch above the bottom of the boat)
so props and heights can be a strange thing to get right.
with a straight out the box engine and motor i would go to highest possible setting and then test it out, much easier to
lower the engine a bit at a time with a block of wood under the skeg and someone using the jockey wheel as my crane up
front to raise or lower the transom.
when raising to extremes is when the jack plates come into play, for these its never going to be the average alloy prop, they
just dont work any good full stop.
if that is your boat in the avatar with the jack plate, then 3 inch below pad is fine to start with as long as you have a
nice stainless prop that can run a touch high and water pressure is still good.
if you want to go realy fast then take it so the drive shaft is dead level with the bottom and get a quality surface prop.
BUT just make sure you still have water pressure !!!!!!!!!!!!!!
once the jack plates and good props come into play ,its also where the low water pick ups come into play as well.
jo average just needs no lower than the boat with the cav plave plate or his performance all round will suffer and
expensive fuel is wasted.
what engine and prop is on your boat NOW
phill