Just bought a Zodiac - need som prop advice

Mattleycrue76 · 11 June 2010, 00:34

I recently purchased a 2001 11'6" Zodiac with a 2002 Mercury 15HP two stroke. It handles great and hits 22 mph with two people on board.

My problem is that I'm using it for diving and the gear is quite heavy. When loaded with two divers and all their gear the boat won't plane and putters along at 6mph.

Current prop is 9x9 eight spline

I'm wondering if going to a 9x8 or even 9x7 would help me plane with all that weight or do I need to go to a bigger motor? I'm guessing that with two divers and gear I'm looking at about 700 - 800 lbs (320-360 kg)

Any input would be greatly appretiated.

Matt

nice.diver · 11 June 2010, 02:21

my 15.5 zodiac sib does 24mph with 40hp loaded with 6 tanks and two sets of gear(garmin gps)
empty it did 23mph(magellian gps)

sorry I am not helping your question

Screaming04 · 11 June 2010, 05:26

9x7 would help but not sure if it will be enough to solve your problem. 15hp is the max for that boat. Check the plate on the transom. It could come down to technique...

Try moving weight forward to get on plane... (have your passenger move forward...driver should get as far forward as possible as well). Once you're on step 15hp will be plenty. Also make sure the floor is fully inflated.

There is also the likely possibility that you are expecting too much from such a small boat... it may not be able to get on plane with that much weight.

Mattleycrue76 · 11 June 2010, 17:05

The rated max power for that boat is 25hp. I realize I'm asking alot of a 15 horse, but as has been mentioned if I can just get on plane it'll be plenty of power to stay there.

jyasaki · 11 June 2010, 20:36

I would try a 7" (if you can find one); it should give you a better launch, but a lower top speed. If you don't have a tach fitted, you may want to be a little careful about running WOT for extended periods with the shorter prop.

BTW, a TinyTach would be a good thing to install: It's small and could hide inside the cowling; it's a non-invasive installation (as I recall), and would allow you to monitor the actual rpm the motor is reaching (which is the right way to figure out the pitch you need.)

jky

Screaming04 · 11 June 2010, 22:44

Quote:

Originally Posted by Mattleycrue76

The rated max power for that boat is 25hp. I realize I'm asking alot of a 15 horse, but as has been mentioned if I can just get on plane it'll be plenty of power to stay there.

If that's the case... that will solve your problem. Get a new prop with the outboard attached.