Outboard motor height??

Hello, i got a 1957 crestliner viking a few years back with a 1962 gale 40hp and the man who i got the boat from told me the boat will be faster if i raise the motor flush with the bottom of the boat. Rite now the cavitation plate sits about 3" below the bottom of the boat and about 2" below the keel thing that goes down the center of the boat. Should i lift the motor up or is it in the corect spot now?

Thanks, Derek

Re: Outboard motor height??

you can raise it so that the anti-cav plate is flush with the lowest point on the keel, but you may see a loss in hard cornering with cavitation. try raising it in one inch increments until you find the sweet spot for best performance and handling.jmo

Re: Outboard motor height??

Apparently OMC had a longer than normal mid section back then due to the different hull shapes and all. If you go to Old OMC (a www a guy in Germany operates) you can look at the sales brochures in there and see just how low the anti vent plate was on some of those boats. Also, back when 25 hp was king of the mountain, speed wasn't that big of an issue....wasn't for me and my running bunch. Well, skeg in the water is nothing but drag so "less is better".

Only caution I have, other than the possible ventilation problem nw mentioned, is getting adequate cooling. On those engines the pickup is not like it is today; down low and forward of the prop, and you don't have a tell tale stream to tell you you are getting adequate cooling water, and you don't have an overtemp alarm. Soooooooo be careful.

Mark

Re: Outboard motor height??

+1 on both posts. While I haven't gone all out an installed a jackplate to raise my '66 20 hp, I did clamp it as high as safely possible on the transom and notice better performance, particularly on the top end. I could probably squeeze a bit more out of it, if I raised it another inch or two, but that would mean a jackplate. Maybe one of these days. Lots of folks in my neck of the woods run in supper skinny water (kneed deep or less), so they jack there motor up as high as humanly possible, but don't set the antivent plate much more than an inch, or so above the keel on these vintage motors as they need to be able to still suck up enough motor to cool the motor.
If you should decide to go the jackplate route yourself, they can actually be made fairly easily using about 4 pieces of aluminum angle and some stainless hardware.

Re: Outboard motor height??

Thanks for all your quick responses! i apretiate them alot, i was looking at the motor last night and it has the clamps that hold it on so as far a lifting it up i dont think i could go much more then a 1/2" higher but would that be enough to increase top speed 1-2mph?

Re: Outboard motor height??

yeah, that's what i did with my motor. I did notice better performance on the top end. Probably picked up a couple mph. Back in the day, racers would use shims as thin as 1/4" to raise/lower the motor to pick up time. If you do decide to clamp your motor up higher on the transom, I would make sure you have a safety chain on it just in case. Here's a how mine is set up.

Re: Outboard motor height??

Thanks for the picture that helps alot! What did u use for a shim? I was thinking of trying paint mixing sticks ading 1 at a time to see the difference it makes then when i got the height where i want it maby buy some wood and make it look nice would that work or would the paint sticks just fall apart?

Re: Outboard motor height??

you can use paint sticks to do lots of fine tuning and trial and error testing, but I don't have any. My motor is simply clamped up as high as I felt I safely could. If you'll notice I also, have a padlock on the transom screw tabs to keep them from accidentally backing out as well as two safety chains. As long as the transom bolts are clamped tight enough, the motor doesn't really need to rest on anything. you'll need a jack plate to raise the motor to the maximum height, but I was able to raise it about 2", which helped.

Re: Outboard motor height??

Use 3ish at a time. You will get bored using one at a time.

Re: Outboard motor height??

ok thanks everybody you have all been a great help! i will start adjusting this weekend and see wat happens.