Prop help 23cc

marlin · #1 07-16-2013, 10:26 PM

I have a 1983 23cc with a 2003 f225 yamaha. I was running a 15p three blade yamaha stainless prop. This prop was on the boat when I bought it. I tried a 17p yamaha three blade that performs better but drags getting out of the hole with a load and wants to fall off plane below 4000 rpm's. (boat has a bracket) Anyone think a 4 blade would help and if so what size and pitch. I am new here so thanks so much for any ideas or experience with similar set ups. Thanks for the great site!

Bushwacker · #2 07-16-2013, 11:07 PM

Any 4B prop will give you more stern lift and allow you to plane at lower speed, which is what you and I both need on our stern heavy rigs with a bracket. A good 3B prop with a lot of blade area like a Merc Mirage+ or a BRP Rebel would probably also help but not as much as a 4B. Can't help you with pitch/diameter info, but I went from a 13.75x17 3B OMC SS prop to a 15x15 4B PowerTech prop and was able to reduce my min planing speed dramatically, from 23-24 mph down to 12 mph, where it used to be with a 300 lb motor on the transom that it was designed for! Hole shot is awesome; boat jumps on plane using only about 45% of full throttle. A Doelfin or equivalent will also help; the 4B and fin will cost you a few mph in top end, and the Doelfin will cost you 0.2-0.3 mpg at cruise although a good 4B prop will probably more than make up for that. Try a 4B prop first, and if that doesn't help enough, then add a fin.

McGillicuddy · #3 07-17-2013, 12:25 AM

Greetings marlin, and welcome aboard.

Every thing you stated suggests that the 15p was actually the better performer. My sense is you got a couple mph more top end with the 17p and are defining that as better performance.

We need more info to really help you. How many RPM at WOT. How many MPH at WOT. What props were/are you running - Yamaha Saltwater Series or what? Be specific here. Different props do different things

At a glance you're running a super heavy motor way back on a bracket.
Is it a modern flotation bracket, or a bit older?

In general, I'll suggest the obvious. Yes a 4-blade will help, 15p, in all likelihood. Widest diameter, biggest-bladed stainless prop you can find. Low rake, little cup. I'm not sure that motor will spin the Mirage.

Normally I would suggest the PowerTech MQS4. 14.5" x 15p. You'll get a little a little more top end with a 3-blade but the weight and is distance aft may govern that decision, and in fact the extra lift of the four-blade might prove advantageous on all counts. The SWS actually has more diameter, its PowerTech counterpart, the OFS series, is 15-1/2" at 15p. If you can turn it, more blade may make the difference in keeping you on plane.

Knowing exactly what prop you're spinning now and your results will help the guys help you out.

Pitch is theoretical relative to performance. The boat, motor, load, and subsequent results should be what define the pitch.

The key is to reach the targeted max. RPMs at wide open throttle with your typical heaviest load.

A picture of your boat at rest would be interesting, and perhaps helpful to see how your center of gravity has changed with the f225 some 30 inches aft the transom. P.S. Do you have trim tabs? I'll assume so, if not, they would definitely help with planing below 4K RPM. They are almost a requirement with a heavier motor on a bracket...

bumpdraft · #4 07-17-2013, 08:52 AM

I have a 1983 cc as well, with a (2005) f225 Yamaha. I have a 15 1/4 x 17 Saltwater Series prop that I used with my 2-stroke engine that I think was perfect for my boat, as long as I could turn the proper rpm. That prop was a little slow "out of the hole" and not turning quite enough with the 4-stroke and I bought a Solas 14 1/2 x 15 four blade that I am currently using. This prop performs well, but is slightly under pitched with a light load. Maybe one day I will get a f250 and put my Saltwater series back on.

Old'sCool · #5 07-17-2013, 09:44 AM

I'm 250 Yam 2S on Hermco bracket w/Solas 17P 4 blade (unsure of dia but 14 1/4 maybe) I lost some top end but it stays on plane at a lower speed and comes out of the hole well. I'm not sure of the 2S/4S difference but would recommend you try it.

marlin · #6 07-17-2013, 01:53 PM

Thanks so much for the help! Sounds like the four blade 15p is what I need. The f225 is fuel efficient and quite but it sucks for torque and low end performance!!

shine · #7 07-17-2013, 02:48 PM

Quote:

Originally Posted by marlin

I have a 1983 23cc with a 2003 f225 yamaha. I was running a 15p three blade yamaha stainless prop. This prop was on the boat when I bought it. I tried a 17p yamaha three blade that performs better but drags getting out of the hole with a load and wants to fall off plane below 4000 rpm's. (boat has a bracket) Anyone think a 4 blade would help and if so what size and pitch. I am new here so thanks so much for any ideas or experience with similar set ups. Thanks for the great site!

Yes! I had the same motor on my 23, and the merc revolution 4 blade in 17 pitch was really great - MUCH better than the 3 blade.

The F225 was stolen and I replaced it with an F250. The 250 swings the same prop in 19 pitch

I highly recommend the 4 blade Merc props