Here's the scoop,
I have a 9000# Baja cruiser with twin 350's, Alpha Gen II drives with 3 bladed Quicksilver SS 19 pitch props. The boat is a slug to get on plain with a load of friends. Points to the sky for a long time even with the drives and tabs buried.
I'm wanting to address this, thinking dropping down to the same props, but in a 17". I believe this will also remove some of the stress the drives will see on take off and help plane out faster. Top rpm could use a little boost too. Speed is not a concern. But I'm wanting to go with AL props since the boat will be water kept yr round to help avoid any galvanic issues with the SS props. Does the 17" sound like the way to go?
There are so many AL props for sale, I have no idea what brand is compareable to my QS props or if there is another factor to consider when going from SS to AL.

Thanks

With Stainless Steel, you will get less flex because they are stiffer. This will increase your whole shot. But, that is not your main problem. I think having 3 blade props is your main problem. When your boat is loaded and you give it the gas, I would assume that you are getting a lot of slip and your props are not grabbing. The more blades you have, the slower you can maintain plane. I had 4 blades and I had to run 3300rpm to stay on plane, also, it took forever to get on plane. With 5 blades, I can stay on plane @2700rpm and my boat gets on plane with no delay. If you go from 3 to 4 blades, you need to reduce your pitch by 2. If you go 3 to 5, I would reduce your pitch by 4.

I don't think slip is my problem on take off. Feels more like too large of a prop keeping the motors bogged down in rpm. Was thinking the smaller pitch of the same 3 blade prop would allow the motors to free up a bit and get more into the hp range. Maybe some flex would be good here? Have considered 4 blade, but the extra blade would really give more bite and don't know if a 2" drop is enough.

Someone else with the same boat went to a 4 blade and dropped to a 17, but stayed with SS, with good results. You'd think I could just follow suit, but I want to go to AL and not sure of the differences. I need more low end power w/o addig more hp.
Thanks

Sorry, I thought when you were getting on plan, that your RPMs were up and you were not getting any bite. I would go down in pitch. Maybe 2" down on 3 blade or 4" on 4 blade.
What is your RPM at WOT and what is it suppose to be?
For very Inch of decreased pitch, you may see 150 more RPM at WOT.

Yes, all bite with no rpm.

Can't recall exactly, been a few months. But I want to say 4500?? I think the motors are spec'd to be 4800. I do know I'm not getting there, so I have room across the board to work with.
Trail would be nice, but changing props in the water would be more of a hassle to try to get the very most. I have no trailer. Hoping to get an recommendation and just going with that.

Call bblades.com.
They have a good reputation.
They should be able to give you some good advise.

A long time ago (2000) we bought a brand new Rinker 232 Captiva ... It had a 260 hp 350 vortec with a 2bbl carb on top. It had a 3 blade QS aluminum prop on the Alpha drive and it was propped about right . Went to the same pitch QS 3 blade SS prop and it could not turn it! I was told it was because the of the flex in the AL prop blades. Instead of changing props to a lower pitch, my buddy and I took the cast iron intake off, replaced it with Air Gap Perfomer intake, a 1" phenolic carb spacer with a little bit of Jim V directed modification, matched spacer to the intake, matched the intake to the heads and matched the other side of the spacer to the new square bore Holley 650 marine carb sitting on top with shiney new K&N marine approved flame arrestor/air filter . After that, I was able to hit the rev limiter with the same QS 3 blade SS prop with no problem. Boat went from 48 mph top speed to 54 mph ... we were flyin' ... Unfortunately all kinds of $hit started flying off the boat, too, like the seat cushions, and various other pieces and parts (that boat was a real POS!).

Anyways, just switching from SS to AL with the same prop dimensions and blade shapes/sizes/diameter, you will gain ~200 rpms, from what I saw on that Rinker. When we swapped the AL QS prop to the SS QS prop, I went from ~ 4700 rpm WOT to ~ 4400 rpm, which was way to low for that engine. After we were done with the carb/intake/spacer change, I was right at the rev limiter with the SS prop (4800 rpm if I remember correctly.)

While you have it apart drop in a couple of mild 454's. Find a couple of used or new take outs. The stock 330's would work fine in that boat since you are not looking for speed. Then you could still use your alpha drives.
Or you could just drop down a couple of pitch in prop. But thats not as fun.