Best way to improve performance

[BIN FSHN]

I have a 2002 Tahoe Q3S/F (17' 10")with a 90hp MercuryELPTO. With a Michigan Wheel 13 1/4 x 19 prop the rpm is 5250 WOT. Max speed per speedometer is 39mph with one full fuel tank and driver only.<br />I want more top end speed and ability to tow skier and tuber with a pasengers in the boat.<br /><br />I'm considering a stainless prop and a hydrofoil on the engine or trading for a larger engine.<br /><br />Any help or suggestions?<br /><br />Thanks

 

[jimmbo]

Re: Best way to improve performance

Go for a larger engine. 39mph on a 17ft from 90hp isn't too bad. A SS prop isn't going to do much much for either acceleration or top speed when compared to what a larger engine will do. Can your boat handle 135 or 150hp? If so an Opti of a new Evinrude E-Tec would be a great choice. Most 4 strokes don't pull like the 2 strokes. And don't let anyone BS about emmissions, the DFI 2 strokes are as clean as any 4 stroke.

 

[BIN FSHN]

Re: Best way to improve performance

Thanks. This is my inclination so far. Any idea what speed improvement I might get from a 135?

 

[walleyehed]

Re: Best way to improve performance

the sole determining factor will be what prop allows max WOT with the engine set-up you choose.

 

[Jdeagro]

Re: Best way to improve performance

Bin Fshn;<br /><br />Let's define performance. You are looking for more top speed and you want to pull a skier with out the bow pointing at the birds overhead. In other words (this only applies to boats) "you want your cake and eat it too". Props are gears in a sense, lower gears will pull skiers better. Higher gears will give you more top speed, assuming the motor torque is enough. The prop size and pitch seems to be pretty close.<br /><br />A bigger engine will give you a little of both but not what you think as the balance of the boat will change with the extra weight on the transom.<br /><br />A hydrofoil will help you a little on the low end but very likely will reduce the top end and make the boat bow steer especially in turns. Additionally the extra lift directly in the center of the boat will have the tendency to make it more unstable side to side, like a teeter totter.<br /><br />I am going to start out here with a statement that is published on this site under our product listing - We have a performance satisfaction guarantee ( your opinion ) or your money back.<br /><br />The most influential component of your boat in terms of performance is the hull itself. Making it more efficient will make it perform better. ie: you will never ski behind a barge. <br /><br />The problem with all boats is that they have a fixed hull design which restricts their performance as the conditions change (speed, water, weight, etc.) Airplane compensate for this by using wing flaps.<br /><br />Boats compensate by using trim tabs. We make Smart Tabs Fully active and automatic for under $200.00) here in the Cleveland area. They are mounted (DIY)on either side of the transom to create more stability especially in turns at high speeds (they keep the boat level so it does not wash out). <br /><br />At slow speeds they are down and keep the stern from dropping on acceleration or at below planing speeds. Because the boat accelerates flat it accelerates faster (at least 10% to 15%). Towing a skier with Smart Tabs is like having a MasterCraft Ski boat.<br /><br />The hole shot is faster and the minimum on plane speed is 35% lower ( your boat would be about 14 MPH). The ride and handling improve because the system, at cruising speeds, is acting like a suspension system on your car. At high speeds, you will be able to trim the motor out more to improve the prop bite, without allowing the boat to porpoise. This will give you and increase in top speed by 2 to 4 MPH.<br /><br />There it is, your cake and eat it too! Do a search on this site to find others who have used them. Or if you want more info, go to www.NauticusInc.com and then don't forget to check the quick links "Boat Balance and Performance" or the magazine editorial tests under "tests". Or if you wish, Call 800-233-0194

 

[b.gagnon]

Re: Best way to improve performance

You unfortunately can't have both without getting a much bigger motor. You can either prop for speed or hole shot.....

 

[BillP]

Re: Best way to improve performance

Towing a skier with Smart Tabs is like having a MasterCraft Ski boat.<br /><br />ROTFL my azz off. Where's the popcorn?

 

[Jdeagro]

Re: Best way to improve performance

BillP;<br /><br />Obviously the MasterCraft will be set up very specifically for towing, with much more power etc, but the point is that with Smart Tabs the boat will have better and more linier acceleration without the high bow rise. Infact the bow rise is typically less than 6 degrees. I am familiar with this boat as we (Boating Life editor and myself) tested one with a 75HP.<br /><br />Bill, some day we will get you into a boat with Smart Tabs so you can see first hand, and then you may not be so down on the product. <br /><br />B.gannon;<br /><br />The low end performance with a "much bigger motor" will not be as good as the current motor with Smart Tabs. The Q3 won't handle too much more. Keep in mind the low end torque is not much different. You guys would be surprised at the performance improvement.

 

[coby-5]

Re: Best way to improve performance

rpm's for that motor should be 5500 at WOT

 

[Capn Mike]

Re: Best way to improve performance

You guys are all missing the obvious ways to increase performance by at least 100%...maybe 200%:<br /> a) if you're using dino oil, switch to synthetic, or; <br /> b) if you're using synthetic oil, switch to dino oil.<br />Did I say 200%? I meant 300%!<br /><br />There. That settles that.

 

[BillP]

Re: Best way to improve performance

nautiJohn,<br />I have great respect for you and your product. If for some reason I ever get a boat that needs that type tab I will buy a pair. But, just because I don't agree with some of your statements doesn't mean I'm down on your product. I've been around many different boats with different foils and never heard or experienced bow steer, turning or teeter totter problems. Those are rare issues, not normal ones as implied. I can use motor trim to have bow steer problems and it wouldn't be accurate to say power trim caused it. Just like tabs, the operator needs to know how to adjust and use foils. You got bow steer?...then trim the motor and get rid of it.<br /><br />You must have different Mastercrafts there. In Florida we see only the ones that look like a sleek Correct Craft Ski-Nautique and are powered by 350cu inboards. No outboard can compare, tabs or not.

 

[walleyehed]

Re: Best way to improve performance

I guess we can have fun (Make fun) of every post, but let's look seriously at this...<br />I see 2 things on this rig that would make a world of difference, performance-wise.<br />#1, I think this would be the perfect application for smart tabs, and #2, I'd send the MWC prop down the road...<br />If we've got the tabs on, we can eliminate about 20 prop choices and simplify this. With the tabs we don't need to worry quite so much about hole-shot, so we can handle a bit more pitch. He's under the RPM figure he should be at now, so if we slap a Stiletto or a Vengeance on there of equal pitch and raise the engine to optimum height, we'll gain the R's back and get closer to 5500, gaining speed and handling charactoristics, period. choice between the 2 props??? go with the Stiletto....<br />This should be the perfect example of what the tabs can do.

 

[b.gagnon]

Re: Best way to improve performance

What are your rpm's with a full load? You could prop it more for speed and make up for the hole shot with the tabs. To me the cost of the tabs(they are a good price) and a prop will get you up to about $500...to me that is not worth 5+- mph. If you can afford a bigger motor than go for it more. Until someone puts an automatic transmission on an outboard Brute HP will rule!<br />Also what is the max hp this boat will take?

 

[b.gagnon]

Re: Best way to improve performance

I found this test report..http://www.boatingworldonline.com/News.htm?CD=472&ID=1403 It shows a bit better performance with a 115.<br />They claim on one of there other pages that this boat can take 150hp..If this is the case I can't see how nautiJohn could be right when saying<br />"B.gannon;<br />The low end performance with a "much bigger motor" will not be as good as the current motor with Smart Tabs. The Q3 won't handle too much more. Keep in mind the low end torque is not much different. You guys would be surprised at the performance improvement." <br />If this boat can truly take a 150hp then his comments are nothing but a sales pitch!<br />The power difference between a 90 and a 150 would be night and day.<br />Look up all his posts with the search function almost all his posts have to do with "smart tabs" Thought that was funny!!!...<br />He may trying to help, and that's great cuz that what this site is for but it sounds like free advertisement and last i checked we as members of Iboats are not allowed to sell on posts.<br />Don't get me wrong tabs work very well and they may be worth the try but nothing beats HP.

 

[walleyehed]

Re: Best way to improve performance

b. gagnon, I think you've missed the point entirely....more HP, does not equal more MPH...<br />6000.00 for 5mph or 500.00 for 5mph.<br />more HP means more weight, more fuel burn, etc.

 

[Jdeagro]

Re: Best way to improve performance

Bill P;<br /><br />Thanks for the compliments! <br /><br />I was not attempting to say that a 90 hp OB would run with the MasterCrafts, what I was trying to project is that the boat will no longer struggle to get up and the acceleration would be more linear like a MasterCraft.<br /><br />With regard to foils, you and I must be exposed to different ends of the market. I talk to people almost on a daily basis and it is very common for me to find that the foils are causing a loss of speed and bow steering. Maybe my exposure is only to the people looking for a solution because they have not been successful with other devices. Maybe it's like the drug enforcement officer who seldom sees the good side. What I can tell you is that if the boat is slowed down with the use of a hydrofoil, it is running with too much stern lift at higher speeds even if the motor trim is used. This could mean that the motor needs to be raised. However, if it is not an OB this is not an option. I have often felt the lack of lateral stability with the use of hydrofoils, which is most apparent in turns at cruising speeds (as the boat leans hard into the turn). If properly set up (which may include raising the motor) they will help with planing as they add additional surface, and may not cause handling problems. If the boat does not do more than 25 MPH then the possible adverse effects may never be felt.<br /><br />b.gagnon;<br /><br />The Q3 is fairly small and a 150 would add seriously to the balance problems. The extra weight would degrade the hole shot and I doubt that the extra HP and torque at the low end would offset the imbalance. The top speed would be better for sure, but the handling would likely suffer.<br /><br />Here is something to think about: Many years ago when the average speeds at the Indy 500 were approaching 200 MPH, they changed the rules to limit the cubic inches of the motors, with the anticipation that the speed would be kept down and the race safer. The chassis builders worked on new designs (engines mounted mid ship) , and the motor manufactures developed smaller lighter engines. The results today are safer races, and speeds in the 250 mph range. With boats the tendency is to look at brute HP and ignore they hull. That is only half of the answer to performance. <br /><br />Oh, by the way, we are the manufacturer of Smart Tabs and Mobster Tabs (for Bass Boats). So I am guilty of bias! I should be.<br /><br />Believe it or not I am trying to help!

 

[BillP]

Re: Best way to improve performance

Skiing behind 90hp with extra people in the boat needs all the hp it can harness. 90hp is marginal for an adult on a slalom course. The best way to get that is flatter props or more hp. Extra speed acquired by using tabs or foils isn't going to compare except for the hole shot. <br /><br />The motor is definitely over propped now. For my money the first $$$ spent would be on a different prop...flatter and smaller dia in 4 blades. The flatter pitch will give more rpms and may increase top speed when not pulling skiers. I would look at tabs (my preference for skiing)and foils only for a better hole shot...if it is needed. If that didn't work I'd look at a bigger motor.<br /><br />NautiJohn,<br />Here's an idea for you. Years back in my ski boat days we made tabs almost full width of the boat...only notched for the motor. The crowd I skiied with favored Stephens SK flat bottom drag boats with outboards around 110hp (I'm dating myself but that was a big motor in the 60s). The full width tabs (1/4" thick 2024 al) helped in a big way for water starts on slaloms. They were attached with ss piano hinge and the adjustments were done with turnbuckles (crude but effective). It took a few runs to dial them in and they stayed in that position.<br /><br />Peace to all.

 

[b.gagnon]

Re: Best way to improve performance

walleyehed ............I'll bet you my house that an extra 60hp on that boat will get more than 5mph... My point is that if 40mph on a 17' boat with a 90hp is not good enough for BIN FSHN then I feel tabs won't help to the degree he is looking for. Besides how long do you think that motor will last running WOT pulling 2 skiers on a regular basis? A v6 carb 150 2stroke merc is only about 100lbs more than the 90hp and the 4cyl 125 2stroke merc is about 50 lbs more so I don't think weight will make much of a difference, besides the boat manufacture knows what that boat can handle way better then any of us. Maybe the best combo would be a 150 with adjustable tabs, this way you get the best of both worlds. Besides he may have his transducers mounted right where the tabs need to go and on a 17' boat there is not much transom space to go around depending on hull design.<br />If there is one thing I have learned in almost 4yrs of being a member on this board is that speed costs money, and lots of it. There is no way of getting around that fact. I don't want to come off like a trim tab hater cuz I personally think every boat should have a pair of adjustable tabs, they help with just about every aspect of performance.

 

[jim dozier]

Re: Best way to improve performance

I have been following this post with interest because I also have a 17' boat which up until a few weeks ago had an 85hp Suzuki on it. It ran right at 40mph with 1 person (GPS). I have just acquired and rigged an OMC 115 but haven't got it in the water because I'm waiting on a steering cable. The 115 is exactly 100lbs more than the 85. My boat is a semi-V hull with a pad bottom and no tabs rated for 120hp. Gimme a week and I'll tell you the difference in the speed and hole shot results.

 

[walleyehed]

Re: Best way to improve performance

b.gagnon, I sure am glad you showed up to tell me how much I don't know...the problem is, I Rebuild boats, from the ground-up. I've had 9 engines on my current 18ft alum, and started with a 70...I now have a "worked" 200 on it. I know what an increase in HP will do on alot of NON-PAD type boats. Your 60HP increase will NOT accomplish what you think it will...it may sound like alot, but it isn't the answer as the hull will limit the speed anyway.<br />With a 150, you still have to prop for the correct RPM for any engine life. Problem there is the boat won't accept the speed without handling issues...where do you stop???<br />I'll bet YOUR house, I could get 5mph more out of Bnfshn's boat with the engine he has. If everyone had the optimum set-up and knew all the tricks, we wouldn't have a forum here, but what do I know.....