motor mount shifts up in waves

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Mehitabell
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motor mount shifts up in waves

Post by Mehitabell »

Hello all,
Does anyone else have the problem that in choppy water the OB motor mount shifts all the way up? This lifts the prop nearly out of the water. The mount (which is adjustable) has a wing nut to lock it in place but it slips. My most recent solution was to build a block of wood that I wedged in but yesterday it broke in half! Any suggestions? Thanks!

Fred
'83 Mac 25
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Jimmyt
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Re: motor mount shifts up in waves

Post by Jimmyt »

Fred,
Any way you could post a pic of your mount so we could wrap our heads around your issue? Sometimes a picture really helps.

Jim
Jimmyt
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NiceAft
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Re: motor mount shifts up in waves

Post by NiceAft »

Indeed Fred,

A close up photo might go a long way to us understanding the “motor mount shifts all the way up”.
Ray ~~_/)~~
Mehitabell
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Re: motor mount shifts up in waves

Post by Mehitabell »

Hopefully these pictures work. The first two are of the mount in the "down" position. The second two pictures are with it up. You can see the locking mechanism right in the middle. It doesn't do much. Thanks for your help!!
Image

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Jimmyt
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Re: motor mount shifts up in waves

Post by Jimmyt »

Great pics.

First Observation: The mount is not fully down. The arms are still angled up towards the motor end, which will tend to force the mount upward with forward thrust. If you can allow the motor to drop such that the arms are angled down toward the motor end, it may make a substantial difference.

Second Observation: The "lock" is a friction slot with wing nut binding. I'm sure Tomfoolery will be able to tell you what the leverage is on this linkage, so I'll leave that to the expert. But, the mounts I'm familiar with have notched positions to provide a positive holding point. It is possible if you have a buddy that can fab stainless (or you can yourself), simply re-designing that link to have positive stops (notches) would do the trick. That way, the wing nut would hold the notch in place, but the notch would hold the mount down.

Let's see what others come up with.
Good luck!
Jim
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Re: motor mount shifts up in waves

Post by NiceAft »

Since this is dependent on friction, can you replace the Wing Nut with a lock nut. Then use a wrench, socket or otherwise to tighten? Maybe also use a large fender washer made of rubber between the bar and the steel washer? I’m just thinking of cheap alternatives to more expensive modifications.

What Jimmy pointed out about the arms being angled upwards is spot on.

If you do angle the mount fully down, is the motor properly immersed in the water?
Ray ~~_/)~~
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Tomfoolery
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Re: motor mount shifts up in waves

Post by Tomfoolery »

The ‘leverage’ on that little lock bar is terrible. For the vertical distance between the two positions, there is only something like one to two inches of travel over the lock. It would have been far better to run the link between the lower pivot point on the motor plate and that lock bolt on the arm. Due to proximity to the rub rail, it might have to be curved, but it’s perfectly doable.

And it should have been notched. If that motor mount is going to be used in only two discreet positions, then a simple bar could be made, of aluminium even, with two positions notched. The OP could even make his own with a few simple tools. If it works out well, a stainless one could be cut, though it would probably have to be done with water jet or plasma cutter.

I had a mount similar to that on my Aquarius, and for normal work only two positions were required, but in rough water, extra deep into the water is a must. With it being off-center quite a lot, really rough water would allow the prop to ventilate with violent pitch and roll. Hard to get anywhere when the prop keeps popping out or at least sucking air, and me having to back off the throttle constantly.
Tom
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AndyVS
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Re: motor mount shifts up in waves

Post by AndyVS »

I would suggest a more robust motor mount. Here is a image of my Garelick mount. Note the notched bar and the difference in leverage. These come in different sizes depending on 2 or 4 cycle and also the weight of the motor.
Image
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Re: motor mount shifts up in waves

Post by chipveres »

Following up on what JimmyT said, I think I see a simple solution. More tilt on the outboard itself would permit you to lower the bracket farther. That would make a straight push on the bracket, minimizing slippage at the wing nut. You do have a lock washer under the wing nut, don't you?

Chip V.
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Re: motor mount shifts up in waves

Post by Starscream »

Mehitabell wrote: Sat Jan 02, 2021 12:29 pm Hello all,
Does anyone else have the problem that in choppy water the OB motor mount shifts all the way up? This lifts the prop nearly out of the water. The mount (which is adjustable) has a wing nut to lock it in place but it slips. My most recent solution was to build a block of wood that I wedged in but yesterday it broke in half! Any suggestions? Thanks!

Fred
'83 Mac 25
All good points, previously. A modern motor mount such as a Panther or Garelick is probably the best solution, but $.

Another possibility: if you look your motor mount, on the bracket portion that's bolted to your boat, there are two pivot bolts more-or-less over top of each other. About 20% of the way down there looks to be a hole through the bracket, between the two pivot bolts. Once the motor is down, you could try something like this: https://www.amazon.ca/Invincible-Marine ... 999&sr=8-4 to hold it in place. I'm assuming that the motor will go farther down than shown in the photo when the boat is in the water?


Here is a photo of a Panther motor mount. You can see that there are two hooks; one to hold the motor in the up position (engaged the photo) and the other to hold it in the down position (hanging down in the photo). Important for reversing, too! You can see that the hole between the two pivot bolts on the Panther mount is filled by a pin designed to engage the hanging hook when the motor is in the down position.

Image
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Jimmyt
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Re: motor mount shifts up in waves

Post by Jimmyt »

Tomfoolery wrote: Sat Jan 02, 2021 6:00 pm The ‘leverage’ on that little lock bar is terrible. For the vertical distance between the two positions, there is only something like one to two inches of travel over the lock. It would have been far better to run the link between the lower pivot point on the motor plate and that lock bolt on the arm. Due to proximity to the rub rail, it might have to be curved, but it’s perfectly doable.

And it should have been notched. If that motor mount is going to be used in only two discreet positions, then a simple bar could be made, of aluminium even, with two positions notched. The OP could even make his own with a few simple tools. If it works out well, a stainless one could be cut, though it would probably have to be done with water jet or plasma cutter.

I had a mount similar to that on my Aquarius, and for normal work only two positions were required, but in rough water, extra deep into the water is a must. With it being off-center quite a lot, really rough water would allow the prop to ventilate with violent pitch and roll. Hard to get anywhere when the prop keeps popping out or at least sucking air, and me having to back off the throttle constantly.
Or... what about a strap with two holes in it through the lower bolt at the motor mount, and use a quick pin where the wing nut is (on a lanyard of course)? Not as nice as a slotted strap with notches, but way easier to make. Seems like you really only need two positions. If you need three (as on your previous boat), drill another hole.
Jimmyt
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Mehitabell
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Re: motor mount shifts up in waves

Post by Mehitabell »

Thanks so much for all the helpful replies! I am. It able to lower the motor much further and be able to easily reach the throttle so unfortunately the angle needs to stay. I removed the sliding bar and replaced it with a strap with two holes in it. I attach the strap (bracket) while still on the trailer and secure with a wing nut. This should keep it from moving up or down. Hopefully testing next weekend. Thanks for all the replies!
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