15 Supersport, yamaha 60, Hydrodynamics Jack plate

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Author Topic:   15 Supersport, yamaha 60, Hydrodynamics Jack plate

M Gould posted 05-11-2012 02:54 PM ET (US)
I recently was reading advice from many in this forum. I have a 1987 Supersport, 2000 yamaha 2 stroke originally mounted all the way down and in the 'blind holes'. I ordered a Hydrodynamics EZ lift for the motor and will be trying a Stiletto 13 1/4 x 17 SS prop. The folks at Hydrodynamics were great to work with and predrilled the holes for the blind mount. When I called Bob's Jack Plates about this, they said any drilling I did would void the warranty.
Hopefully I'll get to try the boat this week. I have a Yamaha digital tach and use a handheld GPS. Thanks to all in the forum for the hints and advice in other posts.
M Gould posted 05-11-2012 02:55 PM ET (US)
Forgot to say in the post a 15 Supersport.
Phil T posted 05-12-2012 09:49 AM ET (US)
In reviewing this product http://www.hydrodynamics-usa.com/e-zliftjackplate.html , I do not understand why you would drill extra holes for blind mounting.
Given the shallow splashwell, I would have expected you to raise the jack plate so that the pre-drilled bottom holes on the transom facing portion of the product cleared the splashwell.
If problematic, I would understand drilling new holes in the transom facing portion higher than as provided to clear the splashwell, but not on the engine bracket portion.
M Gould posted 05-14-2012 08:54 AM ET (US)
The bracket to motor holes were correct. The bracket to transom holes had to be drilled to fit the 'blind hole' mount. It is on the boat and looks to raise motor about 2 inches from previous spot. I hope to test it later this week.
Phil T posted 05-14-2012 10:29 AM ET (US)
While some may disagree, using lags in the blind holes to attach the motor and the bracket is not wise. There is additional stress put on the lags.
If you plug the blind holes and drill the lower holes following the BIA pattern, you can use bolts.
2manyboats posted 05-14-2012 01:59 PM ET (US)
How do you use lag bolts in the blind holes? All my motors had to use bolts in the blind hole on the motor bracket.
M Gould posted 05-14-2012 05:39 PM ET (US)
No lag bolts used. All bolts. They (Hydrodynamics) had to drill holes for the 'blind hole' mount on the bracket to transom mount, as their brackets come in BIA pattern standard. This was to prevent any drilling of the transom.
Russ 13 posted 05-14-2012 08:14 PM ET (US)
I am interested in your results, as I am going to add a jackplate to my 15' also.
Thanks,Russ
2manyboats posted 05-16-2012 02:48 PM ET (US)
The jackplate on my 15 sets back 4 inches. As of now the motor is about 4.25 inches higher than it would be if it was mounted all the way down on the transom. This puts the cavitation plate about 4 inches above the keel. I think I can go up at least another inch.
Keeper posted 05-17-2012 11:27 AM ET (US)
On my old set-up, 1988 Whaler 15 SS, I was running a Bobs 5 inch manual jackplate with a Yamaha 70HP 2-stroke and drilled the jack-plate to match the transom as well.
I don't remember running it that high above the transom, but may have been. It's been out of the water for almost 4-years. The prop I was running was Merc Quiksilver part # 4866138 4A4 19P ( 13 1/2" X 19") I could achieve about 42-43 w myself and 1 other on board, 3 small Odyssey batteries, a trolling motor, & 15 gallons of fuel. I'd assume there are props that would have allowed me to run the motor higher & perhaps grab another mph or so, but since it seemed I was close to max. performance on a 20+ year old motor and I got the prop at a great price, I left well enough alone. The hull is dry w no bottom paint.
I just hung the new Yamaha F70 on there and have a ways to go before launch. I would assume I'll have to raise the jack-plate/motor from where it was (same place) with the Yamaha 2-stroke) to offset the additional weight of the F70. I ordered a yamaha performance series 13 1/4 X 18 stainless steel prop as a baseline and will go from there.
Lastly, when i bought the boat it had one of those Doel-Fins on the motor. Long story short it sucked in rough water. The jack-plate was the single greatest improvement in overall ride and efficiency.
Good luck and enjoy !
M Gould posted 05-21-2012 09:01 PM ET (US)
A little bit of data :
Hydrodynamics EZ lift jack plate on 15 Super Sport with 2000 Yamaha 2 stroke :
On the Waccamaw river in SC in light chop. Ran upstream and down and took average with handheld GPS.
With stock Yamaha 13 x 17 Aluminum prop with Jack plate in down position (which seems to be about where the motor could be mounted at top holes if my holes were correct as stated above)
4000 RPM 24.4 mph
4400 RPM 28.0 mph
5500 RPM 36.7 mph
5600 RPM 37.4 mph
prop gripped well in turns, I could/did not run WOT as I had plenty left at 5600 rpm which is just above max for the motor per Yamaha manual (5500).
I had a heavier load in the test above (2 boys - 12 and 14, total weight 235 lbs)
No boys in boat in test below.
Stiletto 13 1/4 x 17 SS prop, jack plate about 1 inch up from previous setting :
4000 RPM 28.0 mph
4400 RPM 32.3 mph
4900 RPM 38.9 - 39.1 mph
5100 RPM 40.2 RPM (WOT)
motor lost grip in tight turns unless trimmed down significantly
WOT was with light load myself attempting to get low out of the wind and trimming until max speed reached w/o cavitation of prop. Running about 32 mph I could see the the plate was above the water flow. I'm not comfortable raising any higher or may not get enough water to cool the engine.
I have not plugged into any prop calculators, but the Stiletto behaves like a 19 or higher.
I'm amazed at the difference between the 2 props. I plan to try a 4 blade 12/3/4 x 19 aluminum only because I can borrow it to see what happens.
It seems the 60 will not push the Stiletto to full rpm potential.
M Gould posted 05-21-2012 09:20 PM ET (US)
On a side note, I took the 15 out in big water in the Winyah Bay (coast of SC) in 1-2 foot chop with occasional 3 ft, and I am amazed at the handling. Great fun, too.
My boys thoroughly enjoyed it, too.
Tom W Clark posted 05-22-2012 09:07 AM ET (US)

quote:
I'm not comfortable raising any higher or may not get enough water to cool the engine.
No, that's not true at all. The propeller will loose grip entirely long before the motor is so high it cannot get enough cooling water.
If the current mounting position is only the equivalent of one inch higher than having the motor mounted all the way down on the top of the transom, then the motor is about three inches to low.

quote:
Stiletto behaves like a 19...
Yes, that is exactly how we would expect a 17" Advantage to perform.
M Gould posted 05-22-2012 09:30 AM ET (US)
Tom, the motor is mounted about 1 inch above the highest mounting holes if no jackplate was used.
Tom W Clark posted 05-22-2012 11:20 AM ET (US)

quote:
where the motor could be mounted at top holes
You meant to say bottom holes?
OK, that is good, it means it is up about 3-1/4" above the lowest mounting position it could have.
2manyboats posted 05-22-2012 01:03 PM ET (US)
How much is the set back of your jack plate ? It sounds like you could go a little higher.
dgoodhue posted 05-22-2012 01:56 PM ET (US)
I run my 5" setback bob's jack plate with a Stilletto prop at 4" above the keel measuring from a straight edge on the keel to cavatation plate. I was able to get 44mph out of my 60 hp Evinrude with that combo. I guess I would expect a few more mph out of your boat in ideal conditions. Assuming your trimming the motor way out for top speed.
If your used having a motor mounted too low you will find that little trim is needed compared to before. I generally run my motor all the way down and trim it out little when I will be able to run a constant speed.
M Gould posted 05-22-2012 02:23 PM ET (US)
I have a 5 inch setback. I will try to see how high it is above the keel.
M Gould posted 05-25-2012 11:00 AM ET (US)
Updated numbers. Ran again at different settings with my 14 y/o in front of boat, slightly more weight than above runs. River (ICW) was like glass except for large yacht creating large wake which did not look large until we hit it and the 15 Super Sport may have looked like the Tom Clark catching air in the ocean photo. 14 y/o was trying to write and was flying 3 ft above the deck , landed nicely on cushions.
I think my last round of data is not accurate, or at least does not agree with the current data ( my son weights 125 lbs).
Stiletto 13 1/4 x 17 with Hydrodynamics EZ lift jackplate 1.25 inches higher than previous setting, which when approximated with straightedge looks to measure 3 inches above keel measuring to cavitation plate. We ran upriver and down and took average. Using handheld GPS.
3000 rpm 20.6 mph
3500 rpm 25.6 mph
4000 rpm 29.8 mph
4500 rpm 33.4 mph
4700 rpm 35.7 mph
4900 rpm 36.9 mph
This was WOT and I could only achieve more rpm by trimming further. At the speeds until this point I was trimming to what felt the best w/o porpoising. Son lying flat in the bow to prevent porpoising.
5000 rpm 37.7 mph
5500 rpm 39.3 mph
I then put the jackplate to its highest setting which appears to be about 1.5 inches higher than previous ( boat was in water, looking at marks on jackplate). Some cavitation on takeoff unless trimmed all the way in, much cavitation in turns, and did get an overheat alarm briefly when trying to trim running at speed.
4000 rpm 28.0 mph
5000 rpm 36.6 mph
5500 rpm 40.0 mph
5600 rpm 40.4 mph
These were upstream only. Hit overheat alarm although the water stream from the motor was constant. Only lasted a few seconds, let motor cool, Then crusied slowly back to the dock.
Tried the 12 3/4 x 19 four blade aluminum that a friend let me borrow, jackplate back to first setting (about 2.75 inches above keel to cavitation plate)
4000 rpm 29.4 mph
4500 rpm 33.4 mph
5000 rpm 37.3 mph
5500 rpm 39.2 mph (WOT)
Again had to trim excessively to get to 5500 rpm.
This is consistent with the Stiletto behaving like a 19. It seems my motor will not spin either the Stilletto or the four blade to WOT without excessive trim, whichs makes neither prop ideal for daily activities with the family. The original 13 1/4 x 17 aluminum prop will spin too fast, although it is worn, but no major dings. Raising the motor helped performance, but I do not have it 'dialed in' yet. I would like a prop that will run to max RPM without over revving.
As I am on vacation at the coast, I have had some free time for testing.
Tom W Clark posted 05-25-2012 11:20 AM ET (US)
Well, in your first test you hit 39.3 MPH at 5500 RPM. The recommended WOT range for the 2000 Yamaha 60 HP two stroke is 4500-5500 RPM. It seems like it is perfect right there.
M Gould posted 05-25-2012 11:55 AM ET (US)
It would rev to about 5000 rpm easily, then had to trim excessively to get to 5500 rpm. If my son were not in the front I think the boat would have porpoised and/or become too unstable.
Tom W Clark posted 05-25-2012 12:02 PM ET (US)
I think you misunderstand how we prop boats. The ideal goal is not to reach the redline easily, but rather to reach the redline, or close to it, with the boat set up for its very fastest run. My own boat is propped perfectly. It reaches the redline when I am at full throttle and the motors are trimmed to their extreme range. It will not reach its redline if the motors are not trimmed out.
If you prop your boat so it reaches the redline without trimming the motor out, then you will exceed the redline if you ever do. This is exactly what the manufacturer does NOT want you to do. The redline is the do-not-exceed engine speed.
On the other hand, if your WOT engine speed falls within the recommended WOT range then it is fine by them. Your motor has a 4500-5500 RPM range and you are at 5500 RPM when trimmed out. You have propped your boat perfectly. Even without trimming the motor out you reach 4900 RPM, again, well within the manufacturer's recommended range.
If you drop to a 15" Stiletto you will exceed 6000 RPM at WOT, This would be very bad and you do not want to do that.
dg22 posted 05-25-2012 12:44 PM ET (US)
M Gould, If you don't have one, I'd invest in a water pressure guage to keep track of the water flow to cool your motor. We fried our 115 Merc with our jack plate running it high. We thought we were still pulling enough water but apparently not. Well worth the $54.
http://www.overtons.com/modperl/product/details.cgi?r=view&i=73307
2manyboats posted 05-25-2012 01:55 PM ET (US)
My 15 Sport has a 60 Etec on a fixed jackplate with a 4inch setback. Trimmed all the way down, the cavitation plate over the water intakes is 2.75 inches above the keel. Trimmed up to about were I run it the height is 4.75. I normally start out trimmed all the way down, then go up as needed. At wot which is 5700 rpms and about 40mph, the boat does not porpoise no matter how high I trim, just start to slip and slow down. It will porpoise a little at lower speeds if trimmed too high. I am running a stiletto 13 1/4x 19 with a fin called SE Sport 300 on the cavitation plate. I did try running without the fin last trip out and I did slip and lose grip in turns more than with the plate.
I was able to look at the cavitation plate at wot and trimmed out and the trailing edge looked about 2 inches above the water.
The next thing I want to try is to talk my wife into buying a new motor for her small tour boat and give me her old 90 Etec.
M Gould posted 05-25-2012 03:23 PM ET (US)
I appreciate all of the input. I may consider a hydrofoil. I think Clark Roberts recommends them, too. I need to try the boat on my local lake under various loads before making a final decision on the Stiletto. .
Keeper posted 05-26-2012 02:25 AM ET (US)
Good numbers !
Sounds like you just have to pick what works best for you.
I am surprised however, to hear about the overheating alarms . . . YIKES !!!
Thanks for the detailed reports!
Keeper
dgoodhue posted 05-26-2012 07:06 AM ET (US)
I was a little confused by your engine height, did you run the motor at 3", 4.5" and 2.75". I would make smaller steps. For the Stilletto 3" is too low and 4.5" probably too high. I moved my motor a 1/4" at a time initial before fine tuning it. One of the ways I judged he height was making the prop didnt slip when I went wot from 3000rpm (or just on plane). The highest I have had my motor was in the 4 1/4" area and I didn't like the way it handles. if I had to guess 3 3/4" would be a good place to start. The prop has a lot of stern lift and made my boat a wilder ride when it mounted too low from all the lift compare to the OMC sst props I also tried. My OMC props liked about 3.25" so the prop does affect the engine height.
My boat does not porpoise at all unless I am over trimmed at slower plan speeds. My boat actually seems to prefers rearward weight, if I have addition forward weight, i have to trim the motor even further to compensate. As mentioned before it is normal to have to trim the motor for the last rpm. For reference On my boat I have to trim it out for he last 500-600rpm.
M Gould posted 05-27-2012 09:59 AM ET (US)
I did move from 2.75 " to 3.0 " to 4.75 ". I was curious how it would grip all the way up. Not again. I should put it back at 2.75 - 3.0 " and run in my local lake. I am not sure if I want to buy a water pressure gauge, I would rather keep the motor lower and not take a chance with overheating.
dgoodhue - Are you running a hydrofoil ?
Another question - does anyone think a transom saver (the bar from the lower unit to the trailer) is necessary when using a jackplate due to increased stress on the transom, or just don't worry about it, its a Whaler ?
2manyboats posted 05-27-2012 01:05 PM ET (US)
Last trip out with fin back on. Just me in the boat.
3000rpms 19mph
3500rpms 22.5mph
4000rpms 26mph
4500rpms 30mph
5000rpms 35.3mph
5700rpms 39.8mph
M Gould posted 05-28-2012 09:13 AM ET (US)
Your numbers look comparable to mine, thanks for the data. I will look into a fin.
dgoodhue posted 05-29-2012 06:22 AM ET (US)
I do not use a hydrofoil and have no plans to use one. I do not have any issues turning. The only benefit I might see would be the ability to hold a lower planning speed.
M Gould posted 05-30-2012 09:54 PM ET (US)
I was able to run the boat on the lake this evening after work. 6 gallons fuel, cavitation plate about 2.75" above transom, younger son in boat. Lake James in western NC is crystal clear fed from the Linville River, altitude by GPS is 1200 ft above sea level. Air temp 84 degrees, water temp 82 degrees. I do not know how this factors in to performance of boat and engine, but it ran great. I was able achieve 5500 RPM (max) and 40.3 mph. Very quick on plane, and cruised nicely.
Thank you Tom Clark, this is a great prop for this boat (and engine). Now to quit tweaking and enjoy the boat and the lake !
Tom W Clark posted 06-01-2012 10:27 AM ET (US)
1200 feet of elevation will only account for less than half a percent of power loss. The number of people and weight of gear will have a much more profound effect.
Running is freshwater should have slowed you down but actually even at that slight elevation, on a hot day and in freshwater, the boat is performing very well. As I said, I think you've got it dialed in quite nicely.
Enjoy.

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Author	Topic: 15 Supersport, yamaha 60, Hydrodynamics Jack plate
M Gould	posted 05-11-2012 02:54 PM ET (US) I recently was reading advice from many in this forum. I have a 1987 Supersport, 2000 yamaha 2 stroke originally mounted all the way down and in the 'blind holes'. I ordered a Hydrodynamics EZ lift for the motor and will be trying a Stiletto 13 1/4 x 17 SS prop. The folks at Hydrodynamics were great to work with and predrilled the holes for the blind mount. When I called Bob's Jack Plates about this, they said any drilling I did would void the warranty. Hopefully I'll get to try the boat this week. I have a Yamaha digital tach and use a handheld GPS. Thanks to all in the forum for the hints and advice in other posts.
M Gould	posted 05-11-2012 02:55 PM ET (US) Forgot to say in the post a 15 Supersport.
Phil T	posted 05-12-2012 09:49 AM ET (US) In reviewing this product http://www.hydrodynamics-usa.com/e-zliftjackplate.html , I do not understand why you would drill extra holes for blind mounting. Given the shallow splashwell, I would have expected you to raise the jack plate so that the pre-drilled bottom holes on the transom facing portion of the product cleared the splashwell. If problematic, I would understand drilling new holes in the transom facing portion higher than as provided to clear the splashwell, but not on the engine bracket portion.
M Gould	posted 05-14-2012 08:54 AM ET (US) The bracket to motor holes were correct. The bracket to transom holes had to be drilled to fit the 'blind hole' mount. It is on the boat and looks to raise motor about 2 inches from previous spot. I hope to test it later this week.
Phil T	posted 05-14-2012 10:29 AM ET (US) While some may disagree, using lags in the blind holes to attach the motor and the bracket is not wise. There is additional stress put on the lags. If you plug the blind holes and drill the lower holes following the BIA pattern, you can use bolts.
2manyboats	posted 05-14-2012 01:59 PM ET (US) How do you use lag bolts in the blind holes? All my motors had to use bolts in the blind hole on the motor bracket.
M Gould	posted 05-14-2012 05:39 PM ET (US) No lag bolts used. All bolts. They (Hydrodynamics) had to drill holes for the 'blind hole' mount on the bracket to transom mount, as their brackets come in BIA pattern standard. This was to prevent any drilling of the transom.
Russ 13	posted 05-14-2012 08:14 PM ET (US) I am interested in your results, as I am going to add a jackplate to my 15' also. Thanks,Russ
2manyboats	posted 05-16-2012 02:48 PM ET (US) The jackplate on my 15 sets back 4 inches. As of now the motor is about 4.25 inches higher than it would be if it was mounted all the way down on the transom. This puts the cavitation plate about 4 inches above the keel. I think I can go up at least another inch.
Keeper	posted 05-17-2012 11:27 AM ET (US) On my old set-up, 1988 Whaler 15 SS, I was running a Bobs 5 inch manual jackplate with a Yamaha 70HP 2-stroke and drilled the jack-plate to match the transom as well. I don't remember running it that high above the transom, but may have been. It's been out of the water for almost 4-years. The prop I was running was Merc Quiksilver part # 4866138 4A4 19P ( 13 1/2" X 19") I could achieve about 42-43 w myself and 1 other on board, 3 small Odyssey batteries, a trolling motor, & 15 gallons of fuel. I'd assume there are props that would have allowed me to run the motor higher & perhaps grab another mph or so, but since it seemed I was close to max. performance on a 20+ year old motor and I got the prop at a great price, I left well enough alone. The hull is dry w no bottom paint. I just hung the new Yamaha F70 on there and have a ways to go before launch. I would assume I'll have to raise the jack-plate/motor from where it was (same place) with the Yamaha 2-stroke) to offset the additional weight of the F70. I ordered a yamaha performance series 13 1/4 X 18 stainless steel prop as a baseline and will go from there. Lastly, when i bought the boat it had one of those Doel-Fins on the motor. Long story short it sucked in rough water. The jack-plate was the single greatest improvement in overall ride and efficiency. Good luck and enjoy !
M Gould	posted 05-21-2012 09:01 PM ET (US) A little bit of data : Hydrodynamics EZ lift jack plate on 15 Super Sport with 2000 Yamaha 2 stroke : On the Waccamaw river in SC in light chop. Ran upstream and down and took average with handheld GPS. With stock Yamaha 13 x 17 Aluminum prop with Jack plate in down position (which seems to be about where the motor could be mounted at top holes if my holes were correct as stated above) 4000 RPM 24.4 mph 4400 RPM 28.0 mph 5500 RPM 36.7 mph 5600 RPM 37.4 mph prop gripped well in turns, I could/did not run WOT as I had plenty left at 5600 rpm which is just above max for the motor per Yamaha manual (5500). I had a heavier load in the test above (2 boys - 12 and 14, total weight 235 lbs) No boys in boat in test below. Stiletto 13 1/4 x 17 SS prop, jack plate about 1 inch up from previous setting : 4000 RPM 28.0 mph 4400 RPM 32.3 mph 4900 RPM 38.9 - 39.1 mph 5100 RPM 40.2 RPM (WOT) motor lost grip in tight turns unless trimmed down significantly WOT was with light load myself attempting to get low out of the wind and trimming until max speed reached w/o cavitation of prop. Running about 32 mph I could see the the plate was above the water flow. I'm not comfortable raising any higher or may not get enough water to cool the engine. I have not plugged into any prop calculators, but the Stiletto behaves like a 19 or higher. I'm amazed at the difference between the 2 props. I plan to try a 4 blade 12/3/4 x 19 aluminum only because I can borrow it to see what happens. It seems the 60 will not push the Stiletto to full rpm potential.
M Gould	posted 05-21-2012 09:20 PM ET (US) On a side note, I took the 15 out in big water in the Winyah Bay (coast of SC) in 1-2 foot chop with occasional 3 ft, and I am amazed at the handling. Great fun, too. My boys thoroughly enjoyed it, too.
Tom W Clark	posted 05-22-2012 09:07 AM ET (US) quote: I'm not comfortable raising any higher or may not get enough water to cool the engine. No, that's not true at all. The propeller will loose grip entirely long before the motor is so high it cannot get enough cooling water. If the current mounting position is only the equivalent of one inch higher than having the motor mounted all the way down on the top of the transom, then the motor is about three inches to low. quote: Stiletto behaves like a 19... Yes, that is exactly how we would expect a 17" Advantage to perform.
M Gould	posted 05-22-2012 09:30 AM ET (US) Tom, the motor is mounted about 1 inch above the highest mounting holes if no jackplate was used.
Tom W Clark	posted 05-22-2012 11:20 AM ET (US) quote: where the motor could be mounted at top holes You meant to say bottom holes? OK, that is good, it means it is up about 3-1/4" above the lowest mounting position it could have.
2manyboats	posted 05-22-2012 01:03 PM ET (US) How much is the set back of your jack plate ? It sounds like you could go a little higher.
dgoodhue	posted 05-22-2012 01:56 PM ET (US) I run my 5" setback bob's jack plate with a Stilletto prop at 4" above the keel measuring from a straight edge on the keel to cavatation plate. I was able to get 44mph out of my 60 hp Evinrude with that combo. I guess I would expect a few more mph out of your boat in ideal conditions. Assuming your trimming the motor way out for top speed. If your used having a motor mounted too low you will find that little trim is needed compared to before. I generally run my motor all the way down and trim it out little when I will be able to run a constant speed.
M Gould	posted 05-22-2012 02:23 PM ET (US) I have a 5 inch setback. I will try to see how high it is above the keel.
M Gould	posted 05-25-2012 11:00 AM ET (US) Updated numbers. Ran again at different settings with my 14 y/o in front of boat, slightly more weight than above runs. River (ICW) was like glass except for large yacht creating large wake which did not look large until we hit it and the 15 Super Sport may have looked like the Tom Clark catching air in the ocean photo. 14 y/o was trying to write and was flying 3 ft above the deck , landed nicely on cushions. I think my last round of data is not accurate, or at least does not agree with the current data ( my son weights 125 lbs). Stiletto 13 1/4 x 17 with Hydrodynamics EZ lift jackplate 1.25 inches higher than previous setting, which when approximated with straightedge looks to measure 3 inches above keel measuring to cavitation plate. We ran upriver and down and took average. Using handheld GPS. 3000 rpm 20.6 mph 3500 rpm 25.6 mph 4000 rpm 29.8 mph 4500 rpm 33.4 mph 4700 rpm 35.7 mph 4900 rpm 36.9 mph This was WOT and I could only achieve more rpm by trimming further. At the speeds until this point I was trimming to what felt the best w/o porpoising. Son lying flat in the bow to prevent porpoising. 5000 rpm 37.7 mph 5500 rpm 39.3 mph I then put the jackplate to its highest setting which appears to be about 1.5 inches higher than previous ( boat was in water, looking at marks on jackplate). Some cavitation on takeoff unless trimmed all the way in, much cavitation in turns, and did get an overheat alarm briefly when trying to trim running at speed. 4000 rpm 28.0 mph 5000 rpm 36.6 mph 5500 rpm 40.0 mph 5600 rpm 40.4 mph These were upstream only. Hit overheat alarm although the water stream from the motor was constant. Only lasted a few seconds, let motor cool, Then crusied slowly back to the dock. Tried the 12 3/4 x 19 four blade aluminum that a friend let me borrow, jackplate back to first setting (about 2.75 inches above keel to cavitation plate) 4000 rpm 29.4 mph 4500 rpm 33.4 mph 5000 rpm 37.3 mph 5500 rpm 39.2 mph (WOT) Again had to trim excessively to get to 5500 rpm. This is consistent with the Stiletto behaving like a 19. It seems my motor will not spin either the Stilletto or the four blade to WOT without excessive trim, whichs makes neither prop ideal for daily activities with the family. The original 13 1/4 x 17 aluminum prop will spin too fast, although it is worn, but no major dings. Raising the motor helped performance, but I do not have it 'dialed in' yet. I would like a prop that will run to max RPM without over revving. As I am on vacation at the coast, I have had some free time for testing.
Tom W Clark	posted 05-25-2012 11:20 AM ET (US) Well, in your first test you hit 39.3 MPH at 5500 RPM. The recommended WOT range for the 2000 Yamaha 60 HP two stroke is 4500-5500 RPM. It seems like it is perfect right there.
M Gould	posted 05-25-2012 11:55 AM ET (US) It would rev to about 5000 rpm easily, then had to trim excessively to get to 5500 rpm. If my son were not in the front I think the boat would have porpoised and/or become too unstable.
Tom W Clark	posted 05-25-2012 12:02 PM ET (US) I think you misunderstand how we prop boats. The ideal goal is not to reach the redline easily, but rather to reach the redline, or close to it, with the boat set up for its very fastest run. My own boat is propped perfectly. It reaches the redline when I am at full throttle and the motors are trimmed to their extreme range. It will not reach its redline if the motors are not trimmed out. If you prop your boat so it reaches the redline without trimming the motor out, then you will exceed the redline if you ever do. This is exactly what the manufacturer does NOT want you to do. The redline is the do-not-exceed engine speed. On the other hand, if your WOT engine speed falls within the recommended WOT range then it is fine by them. Your motor has a 4500-5500 RPM range and you are at 5500 RPM when trimmed out. You have propped your boat perfectly. Even without trimming the motor out you reach 4900 RPM, again, well within the manufacturer's recommended range. If you drop to a 15" Stiletto you will exceed 6000 RPM at WOT, This would be very bad and you do not want to do that.
dg22	posted 05-25-2012 12:44 PM ET (US) M Gould, If you don't have one, I'd invest in a water pressure guage to keep track of the water flow to cool your motor. We fried our 115 Merc with our jack plate running it high. We thought we were still pulling enough water but apparently not. Well worth the $54. http://www.overtons.com/modperl/product/details.cgi?r=view&i=73307
2manyboats	posted 05-25-2012 01:55 PM ET (US) My 15 Sport has a 60 Etec on a fixed jackplate with a 4inch setback. Trimmed all the way down, the cavitation plate over the water intakes is 2.75 inches above the keel. Trimmed up to about were I run it the height is 4.75. I normally start out trimmed all the way down, then go up as needed. At wot which is 5700 rpms and about 40mph, the boat does not porpoise no matter how high I trim, just start to slip and slow down. It will porpoise a little at lower speeds if trimmed too high. I am running a stiletto 13 1/4x 19 with a fin called SE Sport 300 on the cavitation plate. I did try running without the fin last trip out and I did slip and lose grip in turns more than with the plate. I was able to look at the cavitation plate at wot and trimmed out and the trailing edge looked about 2 inches above the water. The next thing I want to try is to talk my wife into buying a new motor for her small tour boat and give me her old 90 Etec.
M Gould	posted 05-25-2012 03:23 PM ET (US) I appreciate all of the input. I may consider a hydrofoil. I think Clark Roberts recommends them, too. I need to try the boat on my local lake under various loads before making a final decision on the Stiletto. .
Keeper	posted 05-26-2012 02:25 AM ET (US) Good numbers ! Sounds like you just have to pick what works best for you. I am surprised however, to hear about the overheating alarms . . . YIKES !!! Thanks for the detailed reports! Keeper
dgoodhue	posted 05-26-2012 07:06 AM ET (US) I was a little confused by your engine height, did you run the motor at 3", 4.5" and 2.75". I would make smaller steps. For the Stilletto 3" is too low and 4.5" probably too high. I moved my motor a 1/4" at a time initial before fine tuning it. One of the ways I judged he height was making the prop didnt slip when I went wot from 3000rpm (or just on plane). The highest I have had my motor was in the 4 1/4" area and I didn't like the way it handles. if I had to guess 3 3/4" would be a good place to start. The prop has a lot of stern lift and made my boat a wilder ride when it mounted too low from all the lift compare to the OMC sst props I also tried. My OMC props liked about 3.25" so the prop does affect the engine height. My boat does not porpoise at all unless I am over trimmed at slower plan speeds. My boat actually seems to prefers rearward weight, if I have addition forward weight, i have to trim the motor even further to compensate. As mentioned before it is normal to have to trim the motor for the last rpm. For reference On my boat I have to trim it out for he last 500-600rpm.
M Gould	posted 05-27-2012 09:59 AM ET (US) I did move from 2.75 " to 3.0 " to 4.75 ". I was curious how it would grip all the way up. Not again. I should put it back at 2.75 - 3.0 " and run in my local lake. I am not sure if I want to buy a water pressure gauge, I would rather keep the motor lower and not take a chance with overheating. dgoodhue - Are you running a hydrofoil ? Another question - does anyone think a transom saver (the bar from the lower unit to the trailer) is necessary when using a jackplate due to increased stress on the transom, or just don't worry about it, its a Whaler ?
2manyboats	posted 05-27-2012 01:05 PM ET (US) Last trip out with fin back on. Just me in the boat. 3000rpms 19mph 3500rpms 22.5mph 4000rpms 26mph 4500rpms 30mph 5000rpms 35.3mph 5700rpms 39.8mph
M Gould	posted 05-28-2012 09:13 AM ET (US) Your numbers look comparable to mine, thanks for the data. I will look into a fin.
dgoodhue	posted 05-29-2012 06:22 AM ET (US) I do not use a hydrofoil and have no plans to use one. I do not have any issues turning. The only benefit I might see would be the ability to hold a lower planning speed.
M Gould	posted 05-30-2012 09:54 PM ET (US) I was able to run the boat on the lake this evening after work. 6 gallons fuel, cavitation plate about 2.75" above transom, younger son in boat. Lake James in western NC is crystal clear fed from the Linville River, altitude by GPS is 1200 ft above sea level. Air temp 84 degrees, water temp 82 degrees. I do not know how this factors in to performance of boat and engine, but it ran great. I was able achieve 5500 RPM (max) and 40.3 mph. Very quick on plane, and cruised nicely. Thank you Tom Clark, this is a great prop for this boat (and engine). Now to quit tweaking and enjoy the boat and the lake !
Tom W Clark	posted 06-01-2012 10:27 AM ET (US) 1200 feet of elevation will only account for less than half a percent of power loss. The number of people and weight of gear will have a much more profound effect. Running is freshwater should have slowed you down but actually even at that slight elevation, on a hot day and in freshwater, the boat is performing very well. As I said, I think you've got it dialed in quite nicely. Enjoy.