R23 4 blade prop

[tpfahy]

Any 23 owners move to a four bladed prop? Considered a whale tail as a means of adding lift to get on plane with a larger passenger load. Andrew suggested a four bladed prop as an alternative. The stock prop is the Yamaha reliance 14m 14 1/2. Saltwater home in Canaveral.

 

[Shibumi]

I've been looking into the same...mostly for a wider range of response at lower speeds and in choppier water. What I see on Yamaha's website is this: ultima 4 14.25 pitch 13. I'm willing to to give up the top end the stock prop is optimized for in order to gain the hole shot and a wider power band.

The question is whether that is the right prop or not... Whether it overloads the engine in terms of rpm at WOT...and also whether it allows the engine to reach the 5800-6000 that it should/does now.

Would welcome any thoughts on that. I gather this whole prop thing is fairly complicated.

 

[BB marine]

The 4 blade does add lift but I doubt it would add the needed increase. The whale tale would add more lift then the 4 blade if you want to mount one on your motor. They work but I was never a fan of those things. I would look at your trim tab installation. Take a straight edge on the bottom of the boat and measure how high the trailing edge of the trim tab is from the bottom of the boat. The spec is 5/8" above the bottom with the trim ram completely retracted. If you find more then this you are loosing trim range. My Cutwater was 7/8"above the bottom. An easy way to gain more trim range helping with stern lift is lowering the trailing edge by making a shim out of starboard. Place the shim in-between the trim ram and the trim tab plane. Longer bolts will be needed. Make the shim so that the trailing edge of the plane does not go below the bottom of the boat Trim ram fully retracted.


Cut a square shim slightly larger then the footprint of the trim ram mounting bracket. Use the mounting bracket for a template to drill the holes in the shim for the mounting bolts. Place the shim in-between the mounting bracket and the plane. you will need longer 1/4 20 screws. This will lower the trailing edge of the plane gaining more trim.


Measuring the trailing edge. After shim adjustment you want the trailing edge to be no less than 1/4 " above the bottom of the boat with the rams fully retracted.



This is the factory installed trim tab location. This is the leading edge location slightly more then 5/8". A representative at Bennett told me the max dimension should be no more then 1/4" above the bottom to get full benefit of the trim tab. This installation put the trailing edge at slightly more the 7/8 " which should be no more then 5/8" max. With this installation if I had guest on board sitting in the cockpit. I had a hard time seeing forward the bow was riding high.

The installation of drop fins helped a lot with stern lift but is not the answer if you are dry stacking. I used drop fins with real good results along with shimming the trim ram. I plan on Dry stacking next winter in Florida so I removed the drop fins and installed larger trim tabs along with shims to help lift the stern.


Shims made for my Bennett tabs lowered the trailing 5/8" leaving the trailing edge 1/4" above bottom fully retracted. This added 20% more trim range. It is an inexpensive way to gain extra trim range. It can easily be adjusted by making thicker or thinner shims and if negative benefits are not experienced just remove them. A lot cheaper then a new prop!
I hope your enjoying Florida Tim.

 

[Catch22]

A preface here: I have no experience with trim tabs on tugs. BB Marine's post with pics is a super resource for those wanting/needing that fix.
I have had a couple of whale tale successes with both underpowered outboards and boats that tended to porpoise in narrow power band situations. Both resulted in positive bow control at reduced RPM. In one case I did chose to go to trim tabs for a better result, but the non-hull breach and ease of install/removal on the cavitation plate make the whale-tale type fix attractive. All of these were on V-hull boats that may be closer to the planning hull of the 23 OB than a displacement/semi displacement hull.
In short: the whale-tale may be a good beginning point for your quest to compensate for passenger load. I am sure others may have your same question....

 

[BDA]

I recently spent a week at lake Powell, which is at 4,000 feet (with temps over 100), and could only keep about 4200 rpms with the stock Yamaha 14 1/2 x 15 prop on the r23. I plan on getting the 14.25 x 13 pitch 4 blade to see if it will help with more rpms and faster hole shot. Not sure that this will do the trick next year but was fearful of the "whale tale" mount hearing stories of it potential of damaging the metal (fatigue stress), on the motor fins. Any thoughts on propeller selection is sure welcomed. To complicate things, the motor mount on the r23 still fills with water from leaking flexible hose service tube. Have tried various marine silicons to no avail. The newer model has a bilge pump installed.

 

[jagizzi]

Hi BDA,

How do you think water is getting in that tube? I get rain water in there but never salt water so the volumes are quite small. Are you getting water over the swim step somehow?

I'm just trying to get this figured out.

Jim

 

[BDA]

Hi Jim, Water comes over the swim step when slowing from a plane. I poured water around the flexible tube base and water enters around the base edges. I put flexible silicone around the base where the ribbed edges are on the tube. It works for a while, but the tube flexes back and forth when steering and the silicone cracks and fails to keep its seal. I hope that helps, and welcome any other suggestions. Thank you

 

[az9133bm]

We are an Arizona Trailer Boat R-23. Our boat came equipped with the 14.5 x 15 three blade propeller. Fully loaded with a weekend of supplies, full fuel and full water, we were unable to get to WOT. Best we could do was 4900 RPM/32 MPH. Air temp 75 degrees, calm water, with water temp 60 degrees at about 2,000' elevation.

We purchased the Yamaha Reliance Series 14.5 x 13 three blade propeller. Now, at the same lake, under the same loading and conditions, we are able to reach WOT with top speed of 36 MPH. The biggest benefit is being able to plane without using the tabs. Everything about the boat "feels" better.

 

[Rocky Lou]

This thread has a lot of useful information including the trim tab adjustments and whale tale.

I'm planning to order two POWERTECH OFS 4 BLADE PROPELLER - YAMAHA - OFS4-15 1/4 x 17 in place of Yamaha Saltwater Series II 15 1/4 x 19 (3 blade) that came from the factory.

I'm boating offshore where cruising above 25mph is often not possible and my boat cruises best above 30mph. The problem is that at 3500-3600 RPM, which should put me close to 25mph, the boat slips off plane and that is with engine trim all the way down.

The PowerTech guys were referred to me by CW and I spoke to PowerTech support who recommended this 4 blade. They also said I can swap it if I'm not happy. So, I figure there's little to lose, since I was likely going to pick up spare props in any case.

 

[BB marine]

I agree 100% 4 blade to help with stern lift. The Powertech OFS is a rake prop which helps with lift. Its more designed for bow lift which is not needed with a Cutwater. All Cutwaters inboard or outboard are stern heavy requiring all the tab you have to keep the bow down. The Powertech reps know more about their props. I would ask about their SCE4 4 blade cleaver style prop it is designed to add stern lift. The issue with it is max diameter is 14" but made for big Yamaha's. Powertech also makes another four blade for Yamaha outboards that is a good stern lift OSS4 max dia 15". The cleaver will give good stern lift and possibly allow for positive engine trim angle. Buy a pair and swap if they will allow. Trying other props that is the best way to find the right combination.

I'm adding to my post (Edit)

I agree with the drop in pitch 2". When adding additional blades to a prop (3 to 4) there is additional blade area so less slip and better water grip. Your goal is cruising speed issues so most of your engine numbers reflect Rpm at 3600 rpm but posted WOT rpm numbers are not stated. The 300's are considered Yamahas high performance 4.2 L. The engines are rated at 300 hp @ 5500 rpm. When propping always try to maintain the highest recommended rpm WOT. The recommended range is 5000 to 6000 rpm. with the rated hp @ 5500. I don't know the torque curve of this engine but I would put peak torque around 4000 rpm. This would be the rpm for cruise and planning speed normally. If the engines are propped to turn in the middle of the range or slightly lower say 5400 to 5600 when loaded and the engines could be running slightly under the peak torque rpm at cruise. The engines will be lugging and have a hard time keeping the boat on plane. Most don't run WOT in a 30' Cutwater so loosing 1kt @WOT by under propping isn't a big deal.The key is to have a fuel efficient cruise speed where the boat rides and handles good in the 25 to 30 kt cruise. Propping your boat to turn 5800 to 6000 rpm when leaving the dock loaded for your offshore fishing trip can help with the boats handling in the rpm ranges that you operate the boat at 4000 rpm + 800rpm/- 400rpm. The goal would be finding the prop that gives good stern lift, engine rpm in the upper 20% of recommended WOT rpm range (5800 to 6000) rpm.

 

[Rocky Lou]

Brian, I haven't ordered yet, so I will review with PowerTech, thanks. I didn't realize OB and IB Cutwaters were all stern heavy, but, mine is unlike any boat I've ever run and is taking some time to acclimate.

The PowerTech rep admitted he didn't know CWs and looked through his database, not finding any references. He said he'd use Grady White as an example and those are the boats I've owned for 30 years. I'd plan to buy a 330 express when the wife said, "I'm not eating at that tiny table in a dark hole" or words to that effect. GW and CW rides couldn't be more different.

My current WOT is about 5800 RPM and 49 MPH is highest speed noted on Garmin (with SSII Props).

I will be sure to report back with results as I know other owners have similar interests, albeit, we all run in different waters and I am one of the few who primarily run in 'rough' open water. It's not by choice, but, if the tuna are 50 miles out, you can leave on a nice AM and come back in a rough unpredictable sea.

~Paul