New Yamaha F60 props slipping over 20%. Need advice/recommendations.

[arsengo]

New 2005 17" Alumaweld Stryker. Hull deadrise 14" RMV<br />Dry weight: 1030lb, full weight: ~1700lb<br />New 2005 Yamaha F60TLDR 4-stroke 60HP overboard. Gear Ratio: 1.85. Recommended RPM range 5000-6000.<br />Gauges installed: Yamaha digital tach, Eagle SeaChamp 2000C Fishfinder/GPS with speed sensor.<br />No tabs or foils used.<br />Engine broken in, has 25 hours, oil and gear lube changed after the first 10 hours<br /><br />Yamaha aluminum props tested: 1. 11x15 (installed originally by the dealer); 2. 10.75x14; 3. 11.25x13<br /><br />Results:<br /><br />Prop #1 - 4500RPM, 25mph on GPS, 27mph on water<br />Prop #2 - 5300RPM, 29mph on GPS, 31mph on water<br />Prop #3 - 5700RPM, 30mph on GPS, 33mph on water<br /><br />Best performer - 11.25x13<br /><br />Ideally: 5700/1.85x60x13/12/5280 = 38mph<br />Slip: 38 - 30 / 38 = 21%<br /><br />Questions:<br /><br />1. Do I have a problem which can be fixed or my expectations are too high? I was told by the dealer this setup should be able to do 35mph.<br /><br />2. Should I try other props?<br /><br />3. Anything else in the new engine I may need to check and tune up to get better performance?<br /><br /><br />Thank you very much for your help.

 

[ob15]

Re: New Yamaha F60 props slipping over 20%. Need advice/recommendations.

Are you using the GPS or fish finder to get your speed? Have you played around with the trim? Where it the AV plate in relation to the keel of the boat(vertically)?

 

[Silvertip]

Re: New Yamaha F60 props slipping over 20%. Need advice/recommendations.

You have some pretty good numbers to play with so different props at this point in my view is a waste of time. Does the boat get on plane ok or does it struggle? If this is a stern heavy boat (fuel tank, storage, batteries, live well, etc) all in back or toward the back) that will definitely affect performance. Then as Dave F. says, check X-dimension. AV plate should be even or slightly above the bottom of the boat. Are you sure the trottle cable is properly adjusted to get wide open. A 13 or 14 pitch prop should be very close for that engine and boat. Are these cupped props? You might consider Nauticus "Smart Tabs". These are inexpensive (relatively) and can help in these marginal performance situations.

 

[arsengo]

Re: New Yamaha F60 props slipping over 20%. Need advice/recommendations.

Many thanks for the suggestions. <br /><br />my current todo list:<br /><br />1. Check/adjust the throttle cable<br />2. Raise the motor<br />3. As the last resort, install tabs/foils. I hesitate to drill holes in a brand new boat.<br /><br />Here is some additional information to answer your questions:<br /><br />The speed was measured both by GPS and the water speed sensor - Eagle SeeChamp is a FF/GPS combo. The maximum speeds with the engine carefully trimmed for highest RPM/speed are listed in my original post. Each prop has been tested for 15-20 minutes at 7-8AM in dead calm fresh water (lake Washington). All props are standard Yamaha aluminum cupped 3-blade items.<br /><br />The motor is currently installed at the lowest position on the transom. The AV plates are ~0.75inch BELOW the bottom of the boat. It is probably worth mentioning that even though it is deep-V hull design, new 2005 Alumaweld Stryker fishing boats have a variable V (deadrise) with the last 6-7 feet of the keel completely flattened out. The resulting horizontal 'pad' \_/ (depicted with the underscore on this ASCII pic) is 13 inches wide at the rear end of the hull. If the V profile had been uninterrupted for the whole length of the keel, the AV plates would have been positioned slightly above the bottom angle. My friend also owns Alumaweld Stryker made in 2001. His hull has a deep-V profile all the way through.<br /><br />The boat gets on the plane very easily with one person on board. It takes 4 to 6 seconds. To get the better balance, I recycled the cheap battery originally installed next to the engine, and put two new group 24 batteries in the bow storage box under the deck level. There is literally nothing in the stern area, no seats, batteries or fishboxes. The motor itself is only 240lb which was the one of the reasons I decided to buy it (75 and 90HP yamaha 4-stroke motors weigh 370lb).<br /><br />Even though my boat may be somewhat underpowered, I am convinced I am not getting the best performance out of the engine. Today I looked at performance reports on comparable aluminum fishing boats in 16-18 foot range with weights from 1600 to 1800lb equipped with the identical Yamaha 60hp outboard. The reports claim 6000 rpm with a 14-inch pitch prop and speeds up to 34-35 GPS-measured miles per hour.<br /><br />Once again, all suggestions and recommendations will be very much appreciated.

 

[ivar]

Re: New Yamaha F60 props slipping over 20%. Need advice/recommendations.

Maybe with with the batteries relocated to the bow, you have to trim out more to keep the bow out of the water when running wot, which costs efficiency. <br />I'd try to raise the motor, and then try to relocate more of the weight aft again. It may take a little longer to plane , but the boat should need less trim to to get the bow out of the water - and more thrust driving you forward.

 

[ob15]

Re: New Yamaha F60 props slipping over 20%. Need advice/recommendations.

I think you can definitely raise the motor. As Upinsmoke mentioned, the AV plate should be even with or above the keel. Also, if you can trim the motor all the way up and not get any ventilation, you should be able to raise it. If it was me, i'd raise it two holes and try that. It's pretty easy. Remove the top bolts, losen the bottom bolts, use a jack to raise the motor & then reinstall the top bolts.<br /><br />Once it's raised up try using the trim and if it ventialtes towards max trim, then that should be a good setup.<br /><br />Good luck & let us know how it works out.

 

[arsengo]

Re: New Yamaha F60 props slipping over 20%. Need advice/recommendations.

Many thanks to Upinsmoke and Dave F. for all your suggestions.<br /><br />The end result: 36 mph measured by the water speed sensor, 33 mph on GPS.<br /><br />I raised the motor one hole at a time and tested it. With the bracket in the second hole, the AV plates are approx. one inch above the transom's bottom. I have also moved the batteries back to the stern. The boat takes a little longer to get on the plane now, but the engine is happily cranking 5800-5900 rpms and the speed is up another 10%.

 

[ob15]

Re: New Yamaha F60 props slipping over 20%. Need advice/recommendations.

coolness!