US1 Fountain

My cruiser has SS 14" x 19 pitch 3 bladed QS props. Needing something with alot more bite for docking, and not loose any hole shot performance. Not concerned about top end. Wanting to try 4 blades but go with aluminum.
From what I gather a change from AL to SS you'd drop in pitch to stay somewhat equal. And from 3 to a 4 blade would be also require a drop in pitch.
But since I'm going from SS to AL, I assume this would be an increase in pitch???
I'm I correct in thinking to stay with 19" props to keep same performance in order to gain idle speeds bite for docking?

Or any recommendations?
Thanks

FIXX

your problen is the 14'' props on a cruiser which should have at a minimum 15'' prop..if your close to il i have a set of QS 15 3/8 x 19 you can try to see if they work better for you..

US1 Fountain

So you are suggesting a larger 3 blade may be better than a 4 blade? No knowledge with props here.
I'm an hr N of Indianapolis. May just take you up on your offer.
Thanks

bbladesprops

Alpha 4 four blade propellers in the 20 pitch range make good sense for what you are trying to achieve.
4 blade propellers have more blade area and therefore move more water. There aren't many aluminum 4 blade props to choose from and this one works well.
Call if you desire and we can go into more details on your set up.

Brett

FIXX

ok your the prop guy and a good recommendation but on a boat that big he will kill the drives with 4 blades,,he needs a little slip or he will over heat them and they will self district..

US1 Fountain

It's 29' with carbed 350 mags and alpha 1 GenII drives. Dry weight is 9000. 140 gal gas. 35 gal tanks for freshwater and holding. So the weight can add up.
Hole shot is acceptable now. Don't want it to loose any though. I believe full throttle is around 3200-3300 when getting on plain,, with WOT at 4600 when going. . Can get real numbers next couple days. Boat does have a good porpoise to it when trimmed out for a smooth ride. All the tanks/ weight is in back. I have to keep the drives or tabs down to stop the bounce, but then it really is running with a wet surface and rougher ride.

Thanks!

bbladesprops

I'm recommending what the customer is requesting. We do run these props on heavy boats with these drives and don't have the drives falling off the back of the boat. LOL
Driving manners will allow the drives to last. No need to push it out of the hole. Going down a inch of pitch will allow the engines to spool up easier and get on plane with less effort. The manners around the dock will be much better than the 3 blades. These are aluminum props and do not have the geometry of a SS 4 blade prop. These props do slip more than the SS versions.
For what USA is desiring, this is the choice.

Brett

US1 Fountain

Finally got to try different props. Took the 3 bladed SS 19" QS's off and tried the new Merc Alpha4 4 bladed alum props. Tried 18" at 1st. Seemed to have a lot of slip and lost a lot of top end. So ordered the same in 20". Across the board they seem very good. Time to plain is great and boat runs real flat now. Just down 3 mph from the QS props. Docking control 100% better. Main goal here. The 4 blades run best with almost no trim for best handling and speed. I think I was trimming too much with the 18", ( about same as i had to run the 3 blades)thus poor performance. Now that I have the feel for the trim with 4 blades, may kick around picking up some 18's again this winter to unload the drives a bit for a piece of mind. The recommended max RPM is 4400-4800 for these motors. The 18"s let them wind up to 4800 no problem, but I now believe with too much trim. The 20"s hold the RPMs to 4500 max with best speed and ride/ trim