cooling issues

[toddilgen]

guy's i'm stumped, when i run my cat at full throttle water stops coming out of the hole in the side of the hull, but when i back of the throttle and slow down water starts coming out again. my cat is set up with the rudder in-line with the prop, and the hole in the rudder is drilled in line with the prop thrust. what is going on i am stumped on this one. help!

[ReddyWatts]

Can you try a longer rudder?

[toddilgen]

not really, don't want to start taking the boat apart. want to see if i can fix whats already on there.

[FRED]

cooling issues

No comment.

[toddilgen]

do you mean dremel out the groove and open it up more?

[Steven Vaccaro]

Does it come out when you turn at full speed?

[toddilgen]

yes it does the groove is on the right side of the rudder if you are standing behind the boat. when i turn right it comes out.

[Steven Vaccaro]

normally a single drive will need some left rudder defection in order to go down the straight away in a straight line. With the inlet on the right, sometimes the water doesn't flow into the inlet because of this.

[G Doggett]

Maybe the pick up hole is too high.
You say it is in line with the prop blast but sometimes the cone shaped blast has a low pressure area in the centre.
It is better to have the rudder water pick up below the prop, in fact as low as possible.
On my gas cats ( sorry, swear word I know ) I have the water pick up in the bottom of the rudder to get the high volume of cooling water they need.
Graham.