Prop and top speed evaluation

[walleyehed]

Re: Prop and top speed evaluation

lekmedm, Dhadley is here to help...Likely one of the most qualified folks in the country to help with your issues. That plate, or I should say "that hydrofoil mounted to your anti-ventilation plate" (looks like a stingray XP) is a tool and can be a band-aid fix that may or may not work as advertised.
I'm confused by the 2 pics...one has an SS prop, the other looks to be a worn-out aluminum.
Question I would have to throw in would be; Can you verify the tach to be accurate? Kind of a crap-shoot without knowing.
If I may add also, although that boat is a beast for an aluminum prop, the original 15X17 OMC-not the MWC version, has proven to be one of the most efficient aluminum props I've ran, but I have to agree with Dhadley on the fact of performance loss with the alum 3-bld on that size and HP of rig.

 

[lekmedm]

Re: Prop and top speed evaluation

I'm confused by the 2 pics...one has an SS prop, the other looks to be a worn-out aluminum.

Question I would have to throw in would be; Can you verify the tach to be accurate? Kind of a crap-shoot without knowing.

If I may add also, although that boat is a beast for an aluminum prop, the original 15X17 OMC-not the MWC version, has proven to be one of the most efficient aluminum props I've ran, but I have to agree with Dhadley on the fact of performance loss with the alum 3-bld on that size and HP of rig.

The first pic of the blue bottomed boat is my boat. That pic was taken when I was evaluating the boat with a SS prop that later proved to have a spun hub. The second picture is of someone else's boat that is the same model and has the same outdrive. That pic with the aluminum prop simply gave a better view of the outdrive.

Can I verify the tach? Well, no, but I have no indication not to believe it. At any rate, the boat is winterized now.

I didn't know (and never thought) that there were such performance differences between SS and aluminum props. I guess over the winter I'll have the hub on my SS prop fixed.

 

[hwsiii]

Re: Prop and top speed evaluation

Lek, depending on the HP actually being produced by your motor you should be able to run at least 39 MPH with your setup.
You need to remove the hydrafoil from your motor, as everyone else is suggesting, they are actually designed only for boats that can lift the anti ventilation plate completely out of the water when running at cruising speeds and faster. When they are below the waterline at cruising speeds they just create extra drag, especially when the outdrive is trimmed up for maximum speed, because of the water hitting the hydrafoil at an angle. You already have hydraulic trim tabs to help hold the stern up and trim the boat fore to aft and port to starboard and the hydrafoil is just an extra source of drag on your boat.
When you want to attain maximum speed with your boat after you reach planing speed, start raising your outdrive up until you hear the prop start to ventilate or you stop gaining speed and then trim it in just until it quits ventilating or you get maximum speed again. Then adjust your trim tabs up for the correct planing angle and your port to starboard trim is even and you have attained maximum speed.
A Solas Amita aluminum 4 blade prop in a 14 3/4" x 15" pitch prop should raise your speed to about 39 MPH with much less prop slip than you have now, although it could raise your speed to a little over 40 MPH, if your motor is really producing about 350 HP. This prop can be bought on Iboats for about $ 110. In a Stainless prop I would recommend a Baypro II in a 16" pitch, but that prop will probably cost you over $ 400. And I do not believe it will give you a speed increase of more than 2 or 3 MPH maximum over the Solas Amita aluminum. Either one of these props will decrease your prop slip tremendously and give you a much better hole shot as well as increase acceleration throughout your entire RPM range and reduce your minimum planing speed a few MPH.
After saying all of this, if Dhadley recommends another stainless prop than I did, I would buy that one instead of my recommendation, as he has a lot more experience with the high performance SS props than I do.

New Prop Slip with 4 Blade Prop

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[walleyehed]

Re: Prop and top speed evaluation

The tachometer is by far the most important gauge in the boat in your case. It tells how much work is being transfered into results.
The speed is ONE of the results of the proper set-up.
Most tachs of any value may be good for 5-8yrs, some are WAY off from the get-go. I've spent many years testing props now and I can tell you first-hand if the tach isn't right, you're waisting money on props if you have no way of knowing the correct rpm-speed is just a RESULT of the correct set-up with the engine at optimum RPM.
Look at the tach and see if you can get a brand....if it's teleflex and it's 5yrs or older, chuck it. Faria seems to be about the same although I had 3 that all read different RPM at WOT...about 500RPM diff between the 3-just a test of the product.I've found the OEM/OMC-BRP tachs to be most accurate.
A quick note on the Solas props...solas SS props are all 24-10 composition, where-as most Merc, Turbo, Stiletto, Powertech, Early model BRP SS props are of a 15-5 composition which has less flex and tend to wear better, longer. I have tested many of the solas props and most are just fine, with the exception of thier high-performance 3-blds., which require custom set-up and tweaking to get anywhere near the competition.

 

[hwsiii]

Re: Prop and top speed evaluation

Kenny, it is great to see you on the forum and helping people. Did you ever find any of those other performance tests.


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[lekmedm]

Re: Prop and top speed evaluation

You guys are awesome! Thanks so much for all your input. I've even learned so much! Thanks also for those boating tips concerning getting on plane and trimming the outdrive. Boy, am I green...! I'll be taking that plate (hydrofoil) off the outdrive for next season. It's too bad that I won't be able to fully test out all your suggestions since the boat is currently winterized.

Any additional comments/ideas/suggestions are very welcome and appreciated.

 

[walleyehed]

Re: Prop and top speed evaluation

hwsiii, yes, I have all data together now and all on the lap-top. I finally got permission from MWC and Merc to release data.
The best news to report I guess would be the 4 Merc Fury's of E7 tech I got to run last summer. MWC is having a hard time turning out some wheels that will really contend in the top-end of the SS market. I tested a "new design" apollo and reported back the issues I had and I knew they would think I was crazy...as it turned out, the Vender producing this prop....yes, you read that right, had not followed specs on the parabolic rake or cup design and I was told they had to try and recall several thousand props that had been sent to dealers-some already sold..
This prop design has since been picked-up by U.S. builders and performs above average in most applications.
Anyway, I'd like to figure out a way to post all info at some location then link it to this site.
One prop or company that I haven't got to spend the time testing NEW product for that I "really" believe is top-notch is Turbo. They have produced so many new designs and improvements...Dhadley has the handle on most of the new designs and has found some real interesting cross-applications that really speak for the capability of these designs.
The way they have manipulated the way a prop lifts a boat is just amazing.
To date the Turbo1 is still the best performer on my boat.

 

[hwsiii]

Re: Prop and top speed evaluation

Lek, let us know your results after you run the boat.

Kenny, I had always thought that if they would cup the prop from the trailing edge all the way to the blade tip with a progressive cup and used some parabolic rake that it would have to lift the whole boat up even better than the Rev 4.
I heard they were down to less than 70 employees and I am sure releasing that prop like that didn't help them at all.

Kenny, you can use Photobucket to host that information.



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[colsoncj]

Re: Prop and top speed evaluation

I'm currently just getting started trying to determine best prop, expected top speed, etc. I'm currently in a two fold issue, first is getting power trim and trim tabs right to not skew the results, and then determining if everything is setup for best speed.

hwsiii, it really looks like you have the tech know how to really help, and I'm curious if I collected all the data you request in the previous posts if you'd be able to help.

If needed I'd gladly start a new thread as not to hijack or muddle up this thread.

 

[walleyehed]

Re: Prop and top speed evaluation

Yeah, he can help ya out, and yes, it would be best to start a new thread. You are only about 35mi. from me...where do you run at most of the time? I'd be happy to do a 1 on 1 with ya on set-up.

 

[hwsiii]

Re: Prop and top speed evaluation

Col, you better JUMP on that opportunity with Kenny, NOTHING is better than that. You are one lucky man Col.

I'd give anything if I lived that close to him, I would increase my knowledge by 200% in less than 3 months, I am sure.



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[colsoncj]

Re: Prop and top speed evaluation

I usually run at table rock... near shell knob. You arent far from me at all!!!

I'd welcome all the advice and help I can get!

As soon as I get all the info collected on the boat, I'll start a new thread and stick a link back here!