Hydrodyne Performance

[TQUIN45]

Hi- This is my first post. I need help with my 17.6XB Hydrodyne ski boat. It has a 150 Hp Evinrude running a 15 X 17 Al prop. With the motor about level the RPM's are 5200 and the speed is about 41 MPH. With some trim up the RPM's go to 5500 and the speed is 44 to 45 MPH. My question: with this size boat and 150 Hp shouldn't this boat be well over 50 MPH at WOT??? Any help will be appreciated. <br />Tom Quinn<br />PS- the boats accelleration is very strong. Jumps out of the water.

 

[Darren Smith]

Re: Hydrodyne Performance

Many factors relate to the top speed of a boat. Horsepower being only 1. Other things to consider is weight, hull design and cleanliness. With a 150, between 40 and 50 MPH seems reasonable. Just my opinion, and I'm sure others would have a better guess than me...

 

[TQUIN45]

Re: Hydrodyne Performance

Hi again- I found a web site that was advertising this particular boat some years ago. They stated(advertised) performance of 60 MPH with the 150Hp 2 cycle outboard. This is a very good ski boat and fairly sophisticated hull design. <br />Tom

 

[05GlastronSX]

Re: Hydrodyne Performance

i have a 2005 glastron sx 170 w/ a 150 merc xr6 and i saw 55-56 on speedo at about 5300 rpm and it still had some more to go but i backed off. my boat is light at only 1440 lbs dry w/o the engine. adding the engine(400 lbs) gear, a full tank of gas, and people(another 500-600 lbs) id stay my boat weighs about 2400 lbs wet. i dont know how accurate boat speedos really are, but i do believe that i was doing over 50. you should see around 55-60 with that boat without a problem.

 

[Solittle]

Re: Hydrodyne Performance

Tom - Where is the cavitation plate relative to the bottom of the hull? If it is to low then you have unnecessary drag resulting in lower speed. My guess is that you are going to end up raising the engine and possibly going to a 19" prop but lets do one thing at a time.

 

[TQUIN45]

Re: Hydrodyne Performance

Originally posted by SoLittle:<br /> Tom - Where is the cavitation plate relative to the bottom of the hull? If it is to low then you have unnecessary drag resulting in lower speed. My guess is that you are going to end up raising the engine and possibly going to a 19" prop but lets do one thing at a time.

 

[TQUIN45]

Re: Hydrodyne Performance

Your question may be right on target. I pulled the boat out of the lake last night to do a few maintaince items. I checked the cavitation plate- it is about 1 inch below the bottom of the boat. I plan on raising the motor up one hole on sat(today) morning. <br />Can you tell me the best way to attach the lift(chain) to the motor. I have a small tractor with a front end loader- good for about 1000 lbs???<br />I am thinking the engine may then need a 21 P prop since the diameter will go down as the Pitch goes up.I am getting ahead of myself- you are right- one thing at a time.

 

[TQUIN45]

Re: Hydrodyne Performance

I raised the motor up 1 hole this morning, the cavitation plate is now even with the bottom. Someone on this forum had a very clever idea- use the trailer jack to lift the motor. My only concern was the suggested use of the lower unit to push against. I modified the approach and used a piece of 2 X 10 about 29 in long cut at one end to just straddle the motors mounting bracket at the transom. I also had a 1" X 1" notch for the lift hydraulic line. Putting the 2 X 10 under the bracket and then raising the trailers tongue lifted the motor in a nice contolled way. Whole job took about 30 min. Will put in the water tomorrow- I will report the results. Thanks for the help.<br />Tom Quinn

 

[TQUIN45]

Re: Hydrodyne Performance

Originally posted by TQUIN45:<br /> Your question may be right on target. I pulled the boat out of the lake last night to do a few maintaince items. I checked the cavitation plate- it is about 1 inch below the bottom of the boat. I plan on raising the motor up one hole on sat(today) morning. <br />Can you tell me the best way to attach the lift(chain) to the motor. I have a small tractor with a front end loader- good for about 1000 lbs???<br />I am thinking the engine may then need a 21 P prop since the diameter will go down as the Pitch goes up.I am getting ahead of myself- you are right- one thing at a time.

 

[TQUIN45]

Re: Hydrodyne Performance

I did raise the engine by one hole. Cavitation plate is now even with bottom at keel. Tested today .Speed is up approx 2 to maybe 3 MPH. RPM is also up to 5300 in the trim down. Trim up the RPM's went up to 5500 but no increase in speed this round. (Previous numbers before raising engine approx. 5100 and 40 MPH, 5500 and 45 MPH trimmed to first line up. <br />Thanks for the help.) <br />Tom Quinn<br />PS- at some point I will try the next hole up. I am also looking for a 14.5 X 19 prop

 

[BF]

Re: Hydrodyne Performance

Hiya,<br /><br />Hydrodyne's are great ski boats and anytime I've seen one, they've been used as such (not as 60+ mph) lake burners... It'd probably pull stumps with a 17" prop, and would probably hold speed in a slalom pass pretty well... so yes maybe a 19" would be better and would get you a bit more top end. Your rpm's sound good to me. I have a 17' foot ski boat (not a Hydrodyne, more like a Glastron CVX) with a 150 V6 merc and a 19" alum prop... It pulls well and tops out ~46 with no trim, and low 50's with trim. I could probably get another 10 mph out of it with some tweaking and $$$ spent on prop(s), but see no need. It pulls great and is propped for good rpm's. I don't want to have ski boat that won't pull double skiers easily! Like yours, it just jumps out of the hole. I would be curious to try a stainless 21" pitch, but suspect it might make the holeshot a bit sluggish for my liking.<br /><br />good luck.

 

[red10]

Re: Hydrodyne Performance

BF, i have a 17'6 dynatrak ski boat with a 150 johnson and i put a 21 pitch stiletto stainless and she pulls out of the hole very well. The stainless will bite a lot better than the alum and corner better.

 

[Dhadley]

Re: Hydrodyne Performance

TQ45, you might want to think about the 19. 5500 with the 17 is border line lugging now. Work with the set up and gain rpm before going with any more pitch. Dont want to kill the motor. <br /><br />Speaking of motors, which 150 do you have?

 

[BF]

Re: Hydrodyne Performance

thanks red10... yes, I'd be curious as to the difference... just not sure I'm curious to the point of ~$500+. Once it gets 50+ the chine walking starts to get interesting anyway, so like I said more tweaking would likely be required to get all the top end out of the boat. Boat doesn't blow out on corners and works great for what it's used for (tubing/ski boat) so that's why I'm content to spend my $$$ and energy on other things. I do keep my eye on the local boating classified in case a deal too good to pass up comes by on a stainless prop.<br /><br />And Tquin, yes Dhadley has got a point... your rpm's are OK now (I think), but sound a bit low given a 17" prop. I thought the OMC v6's liked being propped around 5500 while the merc's don't mind going closer to 6K? Even so, if I put a 17" prop on my boat, I'm pretty sure I'd be overrev'ing it on the top end (I can reach 6K rpm's now with aggressive trim). Are you sure the motor's healthy? Any chance you're running on 5/6 cylinders? Just a thought... <br /><br />Brent

 

[red10]

Re: Hydrodyne Performance

BF, i gained 4-5 mph bt switching to the stiletto 21 and raising the motor 1 notch, but the whole key was the bite from that prop, you can trim out further but not as far as the raker.

 

[TQUIN45]

Re: Hydrodyne Performance

Thanks to 05GlastronSx, SoLittle, BF, red10, and Dhadley for taking the time to respond. Now there many new questions. First, the engine is a 1988 150 Hp Evinrude.Looks like low hours and good care given by previous owners. Also, a new water pump last fall. I just bought it last fall. Is it healthy ??- I think so. It starts well, idles at 500 to 600 in gear and runs smooth.Any suggested quick tests to verify all cylnders are producing- maybe a compression test??? No unusal vibration. This year 150 does have a longer stroke with a WOT limit of 5500 RPM.<br />Yes to BF- this thing has a stronger hole shot than my(just sold it last summer) Mastercraft ski boat with a 351 Ford. It may pull stumps. Almost shoots out of the water. Is the Dyna-track mentioned by red10 the same boat with a different name as the Hydrodyne 176XB??? <br />I am not trying to create a super speedster- I just felt the boat + engine were not performing for the weight and horsepower.I felt With a 15 X 17 prop the engine should be at 5500 RPM the boat at 45 MPH(calculations support this speed with a 17 P prop).<br />The cavitation plate is now even with the bottom of the boat. I may try to pick up a 14.5 X 19 prop SS to try.Any other suggestions gratefully accepted. <br /> Thanks again to all.<br />Tom Quinn

 

[TQUIN45]

Re: Hydrodyne Performance

Thanks to 05GlastronSx, SoLittle, BF, red10, and Dhadley for taking the time to respond. Now there many new questions. First, the engine is a 1988 150 Hp Evinrude.Looks like low hours and good care given by previous owners. Also, a new water pump last fall. I just bought it last fall. Is it healthy ??- I think so. It starts well, idles at 500 to 600 in gear and runs smooth.Any suggested quick tests to verify all cylnders are producing- maybe a compression test??? No unusal vibration. This year 150 does have a longer stroke with a WOT limit of 5500 RPM.<br />Yes to BF- this thing has a stronger hole shot than my(just sold it last summer) Mastercraft ski boat with a 351 Ford. It may pull stumps. Almost shoots out of the water. Is the Dyna-track mentioned by red10 the same boat with a different name as the Hydrodyne 176XB??? <br />I am not trying to create a super speedster- I just felt the boat + engine were not performing for the weight and horsepower.I felt With a 15 X 17 prop the engine should be at 5500 RPM the boat at 45 MPH(calculations support this speed with a 17 P prop).<br />The cavitation plate is now even with the bottom of the boat. I may try to pick up a 14.5 X 19 prop SS to try.Any other suggestions gratefully accepted. <br /> Thanks again to all.<br />Tom Quinn

 

[05GlastronSX]

Re: Hydrodyne Performance

a compression test will tell you the overall health of the internal componants of the engine likethe rings and gaskets. if it idles well in gear, sounds good, and runs well while getting on and off the throttle, it seems like your engine is a good healthy engine. a compression test will varify this though. i knew that that boat with a 150 should be able to hit 50 without a problem. good luck and have fun.

 

[BF]

Re: Hydrodyne Performance

hiya,<br /><br />just checked back to see if there was an update... another thought, how sure are you about your mph? Any chance your speedo's off? I don't understand your last bit about the speed calculations with a 17p prop... In your first post, you say you hit 5500 and 45 mph with some trim... don't get me wrong, it sounds like you can probably get more out of it, but it doesn't seem like your far from your calculation.<br /><br />As for engine health, yes compression test will tell you something, and you can also give the motor a good run and then pull the plugs and see if they all look the same. Idle of 5-600 sounds a bit low to me. Is that within spec?<br /><br />Brent

 

[red10]

Re: Hydrodyne Performance

BF, dynatrak was made by ebbtide, it weighs 1000 pounds unrigged according to nada. My motor is a 88 johnson gt, basically same as yours so you might want to try a 21 stainless prop and move your motor up 1 notch. Your boat should be close in weight as mine so check your tach and verify gps speeds. good luck