OMC prop vs Solas Prop

[StingRay_90V4]

I have a 92 16ft Stingray v-plane hull with a 90 hp evinrude. The origianl prop was a Omc 13.25dx17p omc prop. The boat had decent hole shot and a top speed of 38-40mph at 5600 to 5800rpm. Depending on load and the weather. On a few calm mornings i have hit 41mph at 5900rpm. Im looking forna new prop as our old omc has hit a sand bar/ rock. Broke one of blades and bent the blade right in half. I am lppking for a new prop. I have an OLD solas prop that is a 13.25dx17p as well. Or at least i think its a solas. Its deffinitly not an omc i dont think. The prop has larger blades. But is the same pitch and diameter. Our boat seems to have gained some bottom end for sure. But lost about 1mph or so at top end. Now getting about 38ish mph top speed. I am wondering what well be any advantages between an omc prop and or solas of the same spec for whole shot and top speed between the two. And ir any other prop i should buy for an extra mph or two. Its all abiut the top end for myself. Lol... Although my motor is still sitting on the bottom gole on the transom and the ac plate ia about an inch BELOW the boat. I NEED TO raise my motor one hole and im sure i will gain at least 1 to 2 mph there also. Im looking for 41 to r2mph. Any advice and or thoughts?

 

[StingRay_90V4]

Nobody has ever had an omc prop and switched to the same pitch from solas and or anither company and notice ANY difference in hole shot and or top speed at all ?

 

[steelespike]

Check out the Turning point Hustler prop in a 16" pitch.Based on your numbers you may be able to use a 17"
They are not as predictable as the Solas but are said to perform like a stainless prop.
Make any changes one at a time and test.The Hustler may allow more height.

 

[batman99]

Not too sure about OMC or Turning Point Props. I've only run Solars 3-blade aluminium and Solars 4-blade aluminum props and both designs worked great. 3-blade is best for faster speed and 4-blade has better hole shot and mid range stability. And, 4-blade has more low speed traction around the dock area as well. My main prop (for my unique 17ft bowrider) has been 4-blade - 2 pitches smaller than my 3-blade. And best of all, Solars props can be bought from iboats Store (and delivered directly to your door). Hope this helps.

 

[StingRay_90V4]

Do you think the solas or omc prop WOULDNT allow me to raise the engine up just ONE whole so that the ac plate is at the same level as the bottom of the hull ? I would think as it is right now i am just draging excess gear case through the water. I can tell for sure the solas prop has more bite then the omc. The boat has gained some bottom end whole shot for sure... If thats the case that the prop does indeed have more bite. Then i would suspect it would allow me to raise the motor up one whole to be even with the bottom of the boat hull. I would imagine .

 

[batman99]

Not too sure why a prop's physical size 'made for your specific engine' would stop the engine from being raised or lowered. Raising or Lowering engine (on its transom holes) is based on the outcome of multiple different water tests - to confirm which is best for you.

Due to the unique hull design of each boat and OB Engine's lower end, its best to adjust your motor up and down to see what works best for you. For a cool video of engine height testing, surf: https://www.youtube.com/watch?v=15QnJHiwkBw

If wondering, my 17 ft bayliner has a heavy weight rear end. After I raised its engine 1 hole (to be almost level with its hull), it ran much better. And, the 4-blade prop (for more stern lift) made it go on plane even faster.

Hope this helps.

 

[StingRay_90V4]

Makes sense. Everyone i have talked to has said by raising my motor up one hole will definitly increase my top speed where my ac plate is about 1 to 1/4 inches below the hull as is. Some people have told me to rise it two holes. But i would think one should be enough. And i will gain 2 to 3 mph by just going up one hole. As well as be slightly better on fuel raised up as well.

 

[steelespike]

Your results from raising the motor would depend on how poorly the height was in the first place.
If the height was ideal you may not get any results.
There is no hard and fast rule about height.I usually suggest to raise the motor to a point just before venting becomes a problem.
4 blade props and props like the Hustler and other performance props may allow more height.
Sometimes an increase in diameter may help resist ventilation.

 

[StingRay_90V4]

What is ventilation ?

 

[StingRay_90V4]

I would think one hole up well srill be ok. I get there is no hard rule of thumb. But i bet i can raise her upnpme hole. From the looks of it. One hole is only about 3\4 of an inch per hole. If that even. My ac plate is over 1.5 inches below the hull bottom. The last owner told me when he bought the new 90 to replace the old 90 mrec he had on it he just dropped the motor as far down as it would go and never bothered to try it any higher. I can tell you compared to my old 87 60hp rude. This boat comes to a stop A LOT FASTER.it really feels like its being pulled to a stop quickly. As compared to my old 60hp that glided to a stop . the old 60 was in the 2nd hole feom the bottom sense the day we bought it drand new. Even after i raise my 90 one hole the ac plate will still be about 3\4 of an inch below the bottom of the hull. Inwouldnt dare try two holes up. But one hole . from what others have even told me on this board. That they have never raised a motor up one hole and had bad results as long as the propnwasnt ABOVE the bottom of the hole.

 

[steelespike]

What is ventilation ?

Some folks call it cavitation but you don't feel cavitation its a different animal
Ventilation is simply when the prop loses its grip on the water usually because air has fouled the prop.
Either from extreme operation or a problem setup.
You should try raising the motor If it seems really low you could go 2 holes. I usually suggest one hole at a time and check.
If you get to a point where there is occasional venting your could try living with it or perhaps a new prop that will resist it better.

 

[StingRay_90V4]

Our motor does seem really low. I should find a pick of the boat in the water so you could see how low it looks on the boat. It really looks like the motor is so low on the boat when you look at the boat side on. It looks like the top of the engine cover is barely visible. Its hard to explain. But hopefully you get whatbim saying. I will look for a pic to upload

 

[StingRay_90V4]

Picture 1 ( Hopefully you get a feel for how low the engine is on the boat. )

 

[StingRay_90V4]

Picture 2

 

[StingRay_90V4]

Picture 3

 

[StingRay_90V4]

This picture is after a massive down pour all night and the bilge pump auto kick in lever stoped working in the 90hp ( The closest boat ). The smaller second boat is our 1987 14' Sunray with a 3 cylinder 60 hp Evinrude. The 90hp is a 16' 1996 StingRay 501ZP. It almost sunk in this picture. Once we got the bilge pump running it took almost an hour to drain all the water,

 

[StingRay_90V4]

That seems to be all of the pics that I can find of the boat that shows the engine at all. Hopefully you can get a feel for what I mean of how low the motor looks on the boat. Where as our 60hp looks like it is a LOT higher on the transom. All though it is only in the second hole from the bottom. you can really tell that it is up higher a lot. The 60 runs EXACTLY the same prop as our 90. Same make, size and pitch. They even have the same part number, The only difference is that on the 60 the prop is only a year or two old. The 90. After destroying its former omc prop. We put an older prop from the 60hp on it. It has a few small dings. A little paint flaking. But all and all. Its in good shape still for a 6 to 7 year old prop. Its wierd, casue with the same prop and the same basic rpm's. The 60 has a top speed of 33-34mph and the 90 ( same prop ) has a top speed of 38-40mph, So I assume its due to a different gear case and gearing ? What would be the ratio of each gear case ? Also , the 60 hp on occasion will blow the prop out and ventilate every blue moon. iT ONLY ever seems to happen when the trim is all the way up at wot and if you take a SHARP turn. It will slip and rev up. Sometimes it still grabs. Sometimes it doesnt. I would say 80% of the time at wot and trim all the way up it will still grab on a sharp aggressive corner. Where as the 90hp. It has NEVER slipped or ventilated at wot and full trim up on a sharp turn at all ever. It really just bits and feels like it is going to throw me out of my seat. It deffinitly handles twice as good as our 60 hp does. I would settle with ONE hole up and an extra n1-2mph gain at top speed and the same or tad better handleing then the 60hp.

 

[Sea Rider]

Before playing raising or lowering engine will need to know exactly where is water flow at speed is passing by lower leg, which nobody checks. Raising prop more and out of its ideal height is like swiming with your fingers wide open. The posted Youtube link doesn't say a thing. Boater is actually playing with trim positions rather than with engine heights on transom. Both are different scenarios and will give different results.

Having that much exposed AV plate out of water throughout the test as seed on vid will give excessive aeration on tight close turns, choppy, windy water cond. Only good for wot runs on flat glass calm waters at straight water courses. That engine needs a rear jack plate or a transom chop down if in pursuit of best performance with any given prop.

Happy Boating

 

[StingRay_90V4]

What YouTube video ?? I have looked at my 90 at wot. And looked at the ac plate. It looks to be just below the water level. Looked like it was causing a lot of spary from what i could tell. I figure if i pull it up one hole it should just skim the top of the water level at wot.

 

[Frank Acampora]

In order to make changes successfully, you need to understand how the engine and hull works through the water. The "cavitation plate" incorrectly named is really an anti-ventilation plate. Its purpose is to provide a physical barrier so the top of the prop does not suck in air due to the negative pressure behind the prop blades. NOW: when the boat is on plane it does not really ride flat on the surface of the water. In fact, it creates a shallow vee shaped hole in the water which is rapidly refilled when the transom passes. Since the transom is lower in the water than the surface, when the water rushes back in, the level is higher than the transom. THUS, if the anti-ventilation plate is below the transom, it is deeper in the water than it needs to be..Extra lower unit will be dragged through the water increasing drag and lowering top speed.

Depending upon the hull design and set-back of the engine, the engine can be raised on the transom up to several inches putting the anti-ventilation plate AT the surface of the water when at plane. This will increase speed but not by a magic number. You need to experiment with different props and engine height settings to achieve best results. ONY change one thing at a time so you can compare results.

Usually, higher pitch will affect hole shot negatively so some high pitch props are vented. This means a controlled amount of exhaust is bled through holes in the hub and ventilates the prop, allowing the engine to rev up easier. Water flow over these holes at speed effectively closes them.