Stainless Prop question

[lciambotti]

I have a 1990 270 Sundancer with twin 4.3L engines alpha I outdrives. I want to switch to stainless props. Any suggestions on what size props would work best?
Thanks

 

[Lazy Daze]

Generally you stick with the same size. You might step down 1" to a 4-blade. But I would question whether you're going to see any noticeable/noteworthy difference in planing or speed. 25 year old V-6's may not necessarily have the torque required to spin up a much heavier prop fast enough to take advantage of the stiffer metal. I don't think it'll be worse, but how much better - if any - is the big question. What's the reasoning for wanting to go to stainless?

 

[dvx216]

If the current props you are using work good then I would go with that pitch . The benifits with stainless steel prop are seen more with high performance boat .The thing you have to consider is their extra weight on the prop shaft and the fact that if you hit some thing with a stainless steel prop being they a stronger might end up damaging the outdrive.

 

[aerobat77]

going from aluminium to stainless may require a little lower pitch , but it depends on the individual installation.

what size you need cannot be answered without information what gearing you have, what size you have now and what rpm,s you reach at WOT with the current props.

 

[lciambotti]

Generally you stick with the same size. You might step down 1" to a 4

I guess my thought was it seemed to help 280 with twin 350's when I owned that boat. I just bought this boat from my brother in law. It has been on stands for 10 years. Based on what I m reading i'll stick with what I have for now. Are there any good outlets for older Searay parts? The boat sat for 8 years before he realized the marina snapped the canvas cover on, but never shrink-wrapped it. So you can imagine the result.
Thanks
Leon

 

[dpmulvey]

If you are going to do anything with the props, I would go with a Piranha composite. Much less unsprung weight. If you hit anything, you are out maybe $100 if you tear up all 4 blades. Stainless is hard and unforgiving. It cost you an outdirve.

 

[Lazy Daze]

The boat sat for 8 years before he realized the marina snapped the canvas cover on, but never shrink-wrapped it. So you can imagine the result.

Ugghhh.

Yeah, sitting for 10 years, you've got many, many more things to take care of before thinking about props.

Ebay, Flounder Pounder marine, and other salvage yards for older Sea Ray-specific parts. But that's really only necessary for hard (fiberglass) parts, for the most part. Most other "bolt-on" things will have been made by another company. Canvas, vinyl, etc... best bet is usually to have a local upholsterer do it. Engine stuff - obviously that's Mercruiser.

 

[lciambotti]

Ugghhh.

Yeah, sitting for 10 years, you've got many, many more things to take care of before thinking about props.

Ebay, Flounder Pounder marine, and other salvage yards for older Sea Ray-specific parts. But that's really only necessary for hard (fiberglass) parts, for the most part. Most other "bolt-on" things will have been made by another company. Canvas, vinyl, etc... best bet is usually to have a local upholsterer do it. Engine stuff - obviously that's Mercruiser.

.

Oh yea. So far three batteries, charger. The Bimini tops were in the cabin, so they are fine. I suspect all/most of the dash switches are bad. The snow and rain got on the dash. Good thing is he had the outdrives in his garage, and I was able to manually turn the engines over. If the fuel gauge is accurate there is about 1/2 tank of ten year fuel in it, but he said he always topped the tank off before storing for the winter. Either way, it needs to be sucked out. I'll post before and after pictures as I progress.

 

[KnotEasy]

Do not even consider the composite props. They flex waaaay to much. Junk. Replacement props whether in stainless or aluminum have a
hub that is desgned to minimize outdrive damage if an underwater strike should occur.

 

[Medin]

I would recommend to step down 1" to a 4-blade stainless prop.

 

[KC_Sundancer]

I would recommend to step down 1" to a 4-blade stainless prop.

I agree 4-blade.
Stainless will have an improvement-less flex under load and the extra blade pushes more water.
We are running 5 blade stainless on our older 270 with 3.8's. They perform great but I have been thinking of trying a pair of 4 blade for comparison.
I would not worry about hitting something with them because of more damage, how often does that happen?
Besides It's not like if you hit something with aluminum nothing happens.

 

[Lazy Daze]

I would not worry about hitting something with them because of more damage, how often does that happen?
Besides It's not like if you hit something with aluminum nothing happens.

Depends on where one boats. Some people boat in shallow lakes/rivers/bays/etc with stumps, rock cropings, ledges. We have a regular prop service where we send out props to be fixed. Damaged props get dropped off all the time.

The advantage to an aluminum prop is that if you do hit something, the prop takes the brunt of the hit since it bends so easily. That way it doesn't transfer the impact through the drivetrain and into the engine. Much less expensive to get a prop fixed (or even buy new) than drive shafts/gears/engine.

 

[aerobat77]

in theory yes lazy dee. in practice a buddy of your marina hit a rock with an aluminium prop on an tohatsu 50 hp outboard and bent the driveshaft.

you cannot say an aluminium will save your drive for sure and a stainless will destroy it for sure, it all depends on the individual sitation how hard you hit what. and i,m not sure if its the right approach in prop selection or boating overall when you assume from the beginning that you will hit something.

that said, on my previous boat with a volvo penta 3.0/SX drive i had a turning point stainless and a turning point aluminium - did not see much difference between them both in performance.- i guess modern aluminiums are just fine for normal use on a V6 engine.