Prop Selection-gctid377849

[Guest]

SwampNut wrote:
I had a Wellcraft 2800 with dual Alpha drives some years ago. It's a 28-footer with 10' beam. I went from aluminum three-blade to aluminum four-blade, and that was a very nice improvement. Then I went to stainless four-blade and that was a HUGE improvement. Do it. You will gain traction and handling around the docks, plane faster and at a lower RPM, and gain fuel economy. It was a win all around.

Did you find you needed more power trim for performance?

[Guest]

itsabowtime2 wrote:
I did it on my 3055 and LOVE the difference. Our boats are similar in size. This is what I got:

Time to plane is now about 7 seconds. Not bad for a cruiser.

I can hold plane at 20mph.

Mid range acceleration is fantastic.

I did not loose any top speed.

And you? What about needing more power trim?

[Guest]

Hill Marine, signature props

I just changed our Bravo 3's to Signature 4 blades. What a differance!

I did loose about 1 MPH top end but now idle to 20 MPH in 8.5 seconds. The old props took forever.

I can stay on plain at less than 20 MPH. Before it was difficult to maintain 23 MPH.

http://www.hillmarine.com/

They are fairly close to you and would probably send a couple sets to try.

[2850Bounty]

dpoelstra wrote:
my set pins are good, I really dont need much trim even with the tabs unless i have 4 of my big 250+lb buddies on board, and they are all sitting on the port seats, or a wind is pusing me to the side. I like all the benefits of going to a four blade, until I read the need for power trim. I would love to hear if anyone knows about this. It seems that the additional trim is only needed once up on plane, so changing the set pins won't solve the problem, if it is in fact, a problem.

The more reading I did, it seems that the diameter has little effect on performance, and its all in the pitch and blade design (cup, etc.).

Anyone go from 3 blades to four, and found that they needed more power trim?

dpoelstra wrote:
And you? What about needing more power trim?

Dan, as noted in your thread, drive trim and trim tabs each perform an entirely different task.

On topic..... these boats tend to be fitted with what I'd consider to be pretty narrow TT Planes.

The Sport Tab "skegs" seem to help as well.

Perhaps Tom w/ Bennett will chime in on that one!

If you were able to trim your 280's, you would trim OUT if anything.

Of course you don't have that ability with these drives, other than the set pin location.

The center set pin position seems to work the best.

I suppose that you could try the AFT-most position, and see what it does, but it's going to affect how well the boat comes out of the hole.

If it comes out of the hole OK......, you should see a benefit while at planing attitude.

As for the 4 blade props, I just don't think that you're going to see these commonly used on your style boat with the AQ series drives.

All you can do would be to give them a try.

.

[Guest]

FL510 wrote:
Hill Marine, signature props

I just changed our Bravo 3's to Signature 4 blades. What a differance!

I did loose about 1 MPH top end but now idle to 20 MPH in 8.5 seconds. The old props took forever.

I can stay on plain at less than 20 MPH. Before it was difficult to maintain 23 MPH.

http://www.hillmarine.com/

They are fairly close to you and would probably send a couple sets to try.

GREAT resource.

I will call them tomorrow. Thanks!!!

Did you have to mess with your drive trim?

Yes, the reading i did is that the drive trim needs to be out once on plane for goo dperformance. My point about the trim tabs was only to comment on the overall trim of the boat. I would not want to set the pins to trim the drive out, as it will kill the hole shot, and that is one thing I would like to improve.

Maybe I will start a new trend???

[Guest]

From the Hill Marine Website...

Pitch Size

Question: When converting from a three blade to a four or five blade should I drop my pitch size?

Answer: Not unless your boat is operating outside it's proper RPM range. Four blades originally got a bad name this

way, dealers would recommend a lower pitch when going to a four blade propeller, the result was spectacular hole shot,

over revving of RPM and significant loss to top end performance.

I heard everywhere to drop an inch of pitch when goin to 4 blades???

[Guest]

ok, I pulled the trigger and bought 4 blades. 17 pitch and 19 pitch (yes I bout FOUR props). Wish me luck. I am just hoping power trim is not needed and it just comes down to pitch selection. Most report going down in pitch, but on the Hill Marine website, which handles high quality and high performance props, they report this is not true. They recomend keeping the pitch the same. We will see.

[2850Bounty]

Dan, I think that you should try two sets of these! They cured my issue!

[Guest]

I'll bet! Unfotrunately, well...you know... $$$$$$:sorrow:

[Guest]

For anyone interested, Bayliner confirmed for me that the 1985 2850 Contessa Sunbridge, with twin VP 225/280 came with 15x19 3 blade props for sea level boats.

I have 14.5x19 and 14.5x17 4 Blade props ordered and comming. Which ones to try first? A high performance prop shop (Hill Marine) says not to dop down in pitch, but the common response it to drop pitch.

I am also worried because Piranah props says power trim is important with 4 blade props, and I don't have power trim.

Open to suggestions and experiences at this point, but once these props hit the water, they are not returnable (iboats.com).

[2850Bounty]

14.5x19 and 14.5x17.

I'm not a prop expert, but I think that for your boat a 14.5" diameter prop, regardless of pitch or blade count, is too small in diameter.

.

[Guest]

2850Bounty wrote:
14.5x19 and 14.5x17.

I'm not a prop expert, but I think that for your boat a 14.5" diameter prop, regardless of pitch or blade count, is too small in diameter.

.

Why is that? The reading I have done from multiple sources, including high performance shops is that diameter is much less of a performance issue than pitch, and a half inch one way or another will make no differnece, especially in a 4 blade prop. 4 blades are much more efficient with less slippage than 3 blades, that unless you are after VERY high speeds and high performance, a half inch in diameter is of little consequence.

I will be testing them this weekend, so we will see. May be a total ($450) failure. I would have stayed with the same diameter, but they were not available in the 15 inch in that line.

Wish me luck.

Still open to suggestins on which ones to try first.

[itsabowtime2]

dpoelstra wrote:
And you? What about needing more power trim?

My wheels are 14.75 x 15. Merc drives however.

As far as trim, the results I get is with zero trim.

[itsabowtime2]

I would go with the 17 first. The 4th blade will lower your WOT RPM's by about 200. Dropping the pitch will compensate for that. You are also dropping in size by 1/2 inch, that will bump up the RPM's by about 50-100.

[Guest]

itsabowtime2 wrote:
I would go with the 17 first. The 4th blade will lower your WOT RPM's by about 200. Dropping the pitch will compensate for that. You are also dropping in size by 1/2 inch, that will bump up the RPM's by about 50-100.

So will the diameter almost completely comensate for the 4th blade if I kept the 19 pitch? I want to try them both so bad just to see the difference, but dont want to flush $220 down the drain by not being able to return them. Grrr.