Chris Cat
 

I have an 1984 Chris Cat with merc 400's and SSM II's. It takes a long time to get on plane - 3 blade cleaver props. Will 4 blades help? Don't know the current pitch- I will check that.

Thanks Wannabe

What diameter prop are you running? 15"?
IMHO 4 blades may help; you'll be limited in diameter because of the #2 drive and might have trouble finding small diameter props.

Changing to a larger diameter 3 blade might help, but you'll need to cut-off the back part of the "anti-cavitation" plate for clearance. Even with the cut, I think you're limited to about 16" diameter.

Also note that the larger diameter & 4 blades will put extra stress on the drives and parts are hard to find.
Due

OK, the planing issue was taken care of this summer. I experimented with the drive settings at launch. Previous owner told me to keep the drives at "0". I tried in October setting at "-2" and boom up on plane in 150 yds. OK, I am learning about this boat.

Wannabe

You have 4" hubs, 4 blade props are non-existant for the 2 drive. There were diameters to 16.5" though. I can't remember how big you cn go with the diameter though.

Brett, I will confirm if 4 inch or 6 inch propshaft length this weekend. I may have to go to used market for larger pitch if I repower.

Wannabe

Your boat presently has a 2" spacer in the drives to promote planing. Also, the props that were on it were 16x28 three blade, which is about right for the power you have. I would encourage installing a ballast tank in the cabin and removing the 2" spacer on the drives. This will help with planing, but also greatly improve top-end performance since the props are presently running partially submerged.

CcanDo

CcAndo:

I was not aware you know so much about the boat. Thank you for the information!!! I will try and attach a picture of the outdrives. I also didn't know I have a spacer- interesting.

The boat planes fine now, I have tried fooling with the drive settings to launch and found the correct settings.

Wannabe

i wnt round and round with similar questions and advice,the person that set me straight and was accurate was hydromotive propellors

Here is the pic. had to resize.

im running 5 blades and a 1" spacer and mine leaps out of the hole with good top end

The aluminum block (spacer) below the trim ram attachment has been added, and again, IMO should be removed. However, it will be much harder to plane (or barely plane at all) once removed. The solution is either a ballast tank or tunnel tab. I question how safe tunnel tabs are on catamarans, so would personally recommend the ballast tank - 30 to 50 gallons.

You should expect 8 to 10 MPH with this change.

CcanDo

Hydromotive doesn't make props for this application.

Don't get rid of the spacers if you take them out. They were put there for a reason.

This will be fun to watch. Keep us informed of the ability to plane corner and the actual speed improvements or losses with your changes and testing.

Speedmasters confirms the spacer, I had no idea it was there. They also confirm i have the 6inch shaft so there may be adaptors to slide on the shaft to allow different props. Ccando- call me please if you can - cell 248-877-1632
I 'd really like to pick your brain on installing a ballast tank.

Wannabe

anything ever come of this???

Wait and see
 

Considering taking the spacers out and adding a ballast tank. Also looking for slightly bigger props.

Wannabe

It looks like you have a bravo or trs drive if so then are you using the p5 props or px5??? I tried to blow up your pic but its tuff to see your drive.

Its the same shaft then a bravo ,,,so the bravo props will fit !!!!
And yes take the spacers out ,,,no need for a balast tank if they are gone !!!