Well; I missed out on a high-five 18-pitch on Ebay this evening for my 75 tournament skier. My wife walked into the room toward the end of the auction and I could not effectively bid, kinda pricy at though at $285 closing. Has anyone had any experience with these? They seem to be the answer for more holeshot on single outboards or i/o's. I currently run a 21-pitch and have tried a 19 with marginal variance in performance. Kevin-
The high fives are awesome. I loved mine. The only down fall is when you "jam it in reverse" in a hurry. It will cavitate. The hole shot is awesome though, and at high speeds the torque steer is less compared to the 3 blades. Greg
This is a different application than your boat. On our ski team's Twin Rig, we get more pull with a three blade Mirage propeller. Our boat has two 200 Hp Mariners on it, and they seem to bite more, even though there are fewer blades, the blades are much larger, and the three blade propeller probably has more blade area in the water. You might try to find a cooperative boat dealer with a larger stock of propellers, and see if the dealer will let you audition different propellers. We did have the High five props, but the mirage seems to pull harder.
Kevinb there are authorized Mercury Dealers that will loan props for you to try. Just check your area. My experience with 5 highs, they are good for pulling a couple of skiers and they do cavitate in hard reverse like dynagreg1 says. The 3 blades do pull harder for multiple skiers. If your running a newer 75hp try the 4 blade. There are a couple of different styles. If I remember correctly go with the lighter prop. I don't know if you have enough hp to turn a heavy prop unless you play with the different size prop plugs that Mercury uses in some of their props. Edd
Hey folks: Thanks for the great info. Just a few points of clarification regarding my current setup, my usage, and my anticipated outcomes with a reprop. My current specs are as follows: Powerplant is a 351 CID; 2 barrel carb; 233hp mercruiser i/o Prop is a 21-pitch; cupped SST merc marine at wide open throttle (WOT) and minimal trim up I'm at 4300rpm and approx 50 mph I use the boat for open water salom and occasional footing; never pull more than one at a time. Most of my time is spent behind inboards (350 CID's, fuel injected, typically with OJ 4 blade prop'ss (pitch unknown) and I'd like to have comprable hole shot. The outcomes would be to improve the holeshot and torque steer (if possible). I'm weighing in around 195 lbs and my setup seems to lag on the pull out compared the ski friends rigs. I also loose quite a bit of power in the corners (dog bones) and would like not to have to compensate as much with the throttle. THe engine is spec'ed for a 21-pitch but I'm thinking that less pitch and an additional blade or two would improve the performance. I don't care if I give up some of the top end speed, but don't want to create too much slippage/cavitation. Thanks, Kevin-
An inboard boat, and a boat with a trimmable outdrive are two different animals. A typical inboard runs a 13x13 prop, at engine speed, tops out around 45-47 mph. A Ski Nautique runs a 16 pitch prop, with a 1.23 reduction, and tops out about 45-47 mph. a ski nautique with a 502 cid engine runs about 52-54 mph, with 120 more hp. The point is, A tournament boat is speed limited by the hull. A boat with a trimmable outdrive, or motor can lift a lot of the hull out of the water at speed, and can be propped to run faster than an inboard. So, you have to usually prop an I/o or outboard faster, so the motor does not overrev at WOT. The boat will accelerate slower, but will end up going faster than an inboard. If you prop a i/o to top out at around 45mph, and it weighs about the same, it should accelerate about the same as an inboard. It probably will overrev if you do not back off the throttle. It will also use more gas because the engine is running more rpm for a given speed.
Make sure the prop you are bidding on is for a V6 or Mercruiser. I don't think they ever made an 18 pitch High 5 for anything more than the inline engines with the smaller gearcase. The odd number pitches are for the V6's and Mercruisers unless yours has a small gearcase.
The Hydrodyne I/O is the only I/O ski boat that I know of. It needs a specific water ski prop and I don't know of any out of the box prop that is really right for it. My outboard is a converted I/O and I ran it as an I/O for 6 years before I converted it. It had a Mercruiser 898 which is a 305 chevy two barrel at 198 hp. I tried a few props and settled for a 17 reworked to a 16. I don't remember what that engine revved to, but I was not worried about it. It was over the Merc limit I'm sure. I just did not spend much time up there. I have learned a lot about props since then and I have different ideas now. I tried a Torque Shift on it which starts out at 11 pitch and changes pitch to prevent over rev. It pulled like a monster with 11 pitch, but I would not recommend that prop for everyday use. The boat is stern heavy and most performance props advertise that they have bow lift which is really stern dig at low speeds. YOU DO NOT WANT THAT. I tried Doel fins and similar fins and they do lift the stern, but they also create rollers in the wake. The drive needs more tuck and I did a little machine work on mine to help that, but not much. A propeller with a lot of rake creates more torque steer. A propeller with tip cup creates stern dig. Those two features should be avoided. If you own the 19 that you tried and if it does not have more rake than a merc aluminum prop I would take it to a prop shop and have them take all of the cup out and re pitch it to an 18. I would personally buy a new Merc aluminum 17 and have the cup removed and try that. If you can find a prop shop that sells them they might remove the cup as part of the sale. The prop guy is probably going to look at you like you are crazy. Don't forget they have no knowledge of props for I/O ski boats. If you feel that it needs more pitch the shop can re pitch it for you. When you arrive at what you want with the aluminum prop and feel you need a steel prop, you could find the closest prop to what you need and have it reworked. You can throw a lot of money away trying fancy steel props. I added another post to your question about torque steer on the hydraulic steering thread also. jim
