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Author Topic:   Raising the motor

Lars Simonsen posted 02-02-2003 05:34 PM ET (US)
My 1998 Dauntless 18 has the motor (135 Optimax) set at the lowest position. The boat gets up on plane easily with minimal bow rise, and the top speed seems to be "normal" (around 42 mph according to my speedo). But when it's on plane, it throws a "V" shaped splash of water, which I've heard is a sign of the motor being to low. The motor also hangs so low that you can't trim it down very far when it is on the trailer, which is sort of a nuisance (and creates the potential for damaging the lower unit when loading the boat). I'm inclined to raise the motor up to the next hole. Even if it doesn't improve the performance of the boat, it would take the lower unit more out of harm's way when the motor is on the trailer. Do I have anything to gain or lose by raising the motor? How do you raise the motor? My neighbor has a chain fall etc, but I'm not sure what part of the motor (other than the mount) can bear the weight of the motor. Is this something that I'm better off letting a boat mechanic do for me? Any advice would be greatly appreciated.
After a couple of weeks of bitter cold, we had a nice day today and took a cruise. There was thin ice at the boat ramp, but nothing too bad. It was pretty chilly, but my wife and kids and I toughed it out and had a nice cruise (crossed the Albemarle Sound and went up the Roanoke River).
Lars
kingfish posted 02-02-2003 05:55 PM ET (US)
Lars-
If your motor is set in the lowest hole, it probably is set too low, and the rooster tail you describe is further evidence of that likelihood. Some motors have a lifting eye under the cowling, which you should remove while lifting under any conditions. I'm not personally familiar with the 135 Opti, but I think there are a number of others here who are, and who could probably tell you just how to rig your motor for lifting.
The telling factor regarding the optimum height for your motor is the relative height of your cavitation plate (or, as has been pointed out by others here, more accurately called the anti-ventilation plate) to the "keel" or lowest point of the transom deadrise of your boat, when the motor is trimmed approximately as it would be when planing. You didn't mention a bracket, so I'm assuming your motor is mounted on the transom; in that case you can raise the motor up at least a couple of holes, until the plate is even with the "keel", or a little above. Conventional knowledge would put the plate of your motor about 1-1/2" above the "keel" for optimum performance. You might try the hole that puts you closest to that measurement, but not beyond it, and if you get ventilation at high speeds and cornering, lower it a hole.
Another consideration for raising your motor for optimum performance is the need for a high performance (at least cupped) prop. If you don't have one now, and don't want to invest in one right now, you'll probably not be able to raise the motor more than one hole above level with the "keel" without getting blowout as I mentioned above.
kingfish
bsmotril posted 02-02-2003 06:10 PM ET (US)
Lars,
You can adjust the motor without a chain or hoist. With the boat on the trailer, you can jack the trailer toungue to move the boat with respect to the trailer. Put a wooden block under the motor skeg and chock the trailer wheels. Now get a couple of big friends to hold the motor at each rear corner. Remove the mounting bolts while they hold the motor steady. Now raise the trailer tongue to lower the transom until the holes match up with the next lower set. Insert bolts, tighten, buy friends a beer.
BillS
Lars Simonsen posted 02-02-2003 06:51 PM ET (US)
Thanks for your help! The cavitation plate does appear to be even with the lowest point on the keel. I have the OEM prop on the motor, which is cupped (I just got it back from the prop shop, and it appears to be a little less cupped than it was before I dinged it up).
I think I'll move it up one hole for now and see how that works. The motor is on the transom, and I don't recall seeing a lifting eye on the motor anywhere (but I haven't specifically looked for it, either.) Bill's method, or some facsimile thereof, sounds doable.
Thanks again for the help!
Clark Roberts posted 02-03-2003 07:25 AM ET (US)
Lars, the Merc has an internaly threaded cylinder (concentric to flywheel nut) to which is affixed a lifting eye (special tool which you most likely can borrow from dealer) which has external threads. If you can't get a lifting eye you can lift engine via a sling under pan fashioned from strap like the trailer hold-down straps...etc.. use some padding so straps won't scratch...Happy Whalin... clark
Lars Simonsen posted 02-03-2003 09:04 AM ET (US)
Yes, I think I know the part you are talking about. Is it the internally threaded hole in the middle of the flywheel on top of the motor? (I had assumed it was threaded for a flywheel puller, which perhaps is another use).
Lars
Clark Roberts posted 02-03-2003 10:34 AM ET (US)
Lars, that's the one! Clark

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Author	Topic: Raising the motor
Lars Simonsen	posted 02-02-2003 05:34 PM ET (US) My 1998 Dauntless 18 has the motor (135 Optimax) set at the lowest position. The boat gets up on plane easily with minimal bow rise, and the top speed seems to be "normal" (around 42 mph according to my speedo). But when it's on plane, it throws a "V" shaped splash of water, which I've heard is a sign of the motor being to low. The motor also hangs so low that you can't trim it down very far when it is on the trailer, which is sort of a nuisance (and creates the potential for damaging the lower unit when loading the boat). I'm inclined to raise the motor up to the next hole. Even if it doesn't improve the performance of the boat, it would take the lower unit more out of harm's way when the motor is on the trailer. Do I have anything to gain or lose by raising the motor? How do you raise the motor? My neighbor has a chain fall etc, but I'm not sure what part of the motor (other than the mount) can bear the weight of the motor. Is this something that I'm better off letting a boat mechanic do for me? Any advice would be greatly appreciated. After a couple of weeks of bitter cold, we had a nice day today and took a cruise. There was thin ice at the boat ramp, but nothing too bad. It was pretty chilly, but my wife and kids and I toughed it out and had a nice cruise (crossed the Albemarle Sound and went up the Roanoke River). Lars
kingfish	posted 02-02-2003 05:55 PM ET (US) Lars- If your motor is set in the lowest hole, it probably is set too low, and the rooster tail you describe is further evidence of that likelihood. Some motors have a lifting eye under the cowling, which you should remove while lifting under any conditions. I'm not personally familiar with the 135 Opti, but I think there are a number of others here who are, and who could probably tell you just how to rig your motor for lifting. The telling factor regarding the optimum height for your motor is the relative height of your cavitation plate (or, as has been pointed out by others here, more accurately called the anti-ventilation plate) to the "keel" or lowest point of the transom deadrise of your boat, when the motor is trimmed approximately as it would be when planing. You didn't mention a bracket, so I'm assuming your motor is mounted on the transom; in that case you can raise the motor up at least a couple of holes, until the plate is even with the "keel", or a little above. Conventional knowledge would put the plate of your motor about 1-1/2" above the "keel" for optimum performance. You might try the hole that puts you closest to that measurement, but not beyond it, and if you get ventilation at high speeds and cornering, lower it a hole. Another consideration for raising your motor for optimum performance is the need for a high performance (at least cupped) prop. If you don't have one now, and don't want to invest in one right now, you'll probably not be able to raise the motor more than one hole above level with the "keel" without getting blowout as I mentioned above. kingfish
bsmotril	posted 02-02-2003 06:10 PM ET (US) Lars, You can adjust the motor without a chain or hoist. With the boat on the trailer, you can jack the trailer toungue to move the boat with respect to the trailer. Put a wooden block under the motor skeg and chock the trailer wheels. Now get a couple of big friends to hold the motor at each rear corner. Remove the mounting bolts while they hold the motor steady. Now raise the trailer tongue to lower the transom until the holes match up with the next lower set. Insert bolts, tighten, buy friends a beer. BillS
Lars Simonsen	posted 02-02-2003 06:51 PM ET (US) Thanks for your help! The cavitation plate does appear to be even with the lowest point on the keel. I have the OEM prop on the motor, which is cupped (I just got it back from the prop shop, and it appears to be a little less cupped than it was before I dinged it up). I think I'll move it up one hole for now and see how that works. The motor is on the transom, and I don't recall seeing a lifting eye on the motor anywhere (but I haven't specifically looked for it, either.) Bill's method, or some facsimile thereof, sounds doable. Thanks again for the help!
Clark Roberts	posted 02-03-2003 07:25 AM ET (US) Lars, the Merc has an internaly threaded cylinder (concentric to flywheel nut) to which is affixed a lifting eye (special tool which you most likely can borrow from dealer) which has external threads. If you can't get a lifting eye you can lift engine via a sling under pan fashioned from strap like the trailer hold-down straps...etc.. use some padding so straps won't scratch...Happy Whalin... clark
Lars Simonsen	posted 02-03-2003 09:04 AM ET (US) Yes, I think I know the part you are talking about. Is it the internally threaded hole in the middle of the flywheel on top of the motor? (I had assumed it was threaded for a flywheel puller, which perhaps is another use). Lars
Clark Roberts	posted 02-03-2003 10:34 AM ET (US) Lars, that's the one! Clark