350HP Yamaha Motor support, finally made one.

[FIRE UP]

Gang,
I asked about this sometime last year but, didn't really get any answers I was looking for. After quite a bit of looking around, I finally found one that was near us in a local Bass and tackle shop. Well, it didn't work, wrong dimensions. So, I decided to simply make one. I purchased a 1" x 12" x 18" HDPE cutting board from Amazon for about $16 or so. I basically remembered the shape of the one I purchased but took back several months ago and, cut out two of them in the shape I thought I needed. I used a table saw to cut the basic blocks out then, I used a band saw to cut the details. I was originally going to make it double thickness from end to end and side to side. But, about 1/4 into the build, I found I couldn't make it double thickness where it would contact the motor steering pivot bracket.

But, I could have it double thickness at its base. So, I cut one off a few inches short. Then, I lined them up and screwed the two halves together with some stainless 10-24 x 2" screws. Once it was all together and edges all sanded and prepped, I laid out the lines for the critical drilling of the 3/4" holes needed for the power tilt rams to enter into. The way this unit is designed, those power tilt rams need to go all the way through the support so that the support rests on the bases of the power tilt rams and the rams do no supporting of the motor what so ever.

The rams themselves are measured very close to just a couple of thousandths over 11/16". I figured a 3/4" drilled hole, will do. But, those holes must be as close to precise as possible because, the clearance for the rams is very, very little. Then, those rams are parallel for at least 4" or more. I don't have the proper milling and drilling equipment for this kind of precise work. So, all of it must be done by hand and my old eyes. I used a 3/4" Forstner bit to drill those holes. That way I had better control. It took a bit of patience but, I got both holes drilled relatively parallel, how about that!!!!! Then, I checked for fit and, imagine that, IT WORKS. It supports that F-350 350 Yamaha V-8 rather nicely without putting a load on any hydraulic parts.

Once it was all checked out and made sure there was no fitment issues, I simply used a hand held deburring tool to round over all the edges and make it nicer to handle. Anyway, see what you think. I know that some of you really don't have any issue trailering your Benny's with that large of a motor either sitting against the power trim rams or, all the down since the prop is still pretty high off the ground, even with the motor in the fully lowered position. But, we have some angled streets around here that can present an *angle of departure* situation that makes that prop come dangerously close to the ground. And, tilting the motor up, now puts a shock load on all the components that are used for tilting the motor, when your running on rough, un-even roads, concrete seams and all that. So, this is why I did what I did.
Scott

 

[dannyleininger]

Nice work Scott!

 

[PartyBarge]

Good ideas! When I used to tow, normally used some method to support the tilted motor or I/O unit. However all of those (as best I remember) were metal mechanical stops or hangers. Yours should afford some shock absorption. I would expect, over time, the contact points will take a beating, but that is a good point for this devise. Of more concern would be the four smallish screws holding the halves together. Your F350 is going to give them a workout if there is much rough road. Maybe version two could be whittling on a solid block that starts out at least two inches thick?

 

[Michiman]

Scott, thanks for taking the time to share your solution! Maybe you should be seeking a patent...

 

[FIRE UP]

Good ideas! When I used to tow, normally used some method to support the tilted motor or I/O unit. However all of those (as best I remember) were metal mechanical stops or hangers. Yours should afford some shock absorption. I would expect, over time, the contact points will take a beating, but that is a good point for this devise. Of more concern would be the four smallish screws holding the halves together. Your F350 is going to give them a workout if there is much rough road. Maybe version two could be whittling on a solid block that starts out at least two inches thick?

PartyBarge,
In the oooolllllddd days, yes, most of those *struts* were there to support an outboard motor, to keep from putting excess stress on the transom of a boat. The support(s) would connect between the motor and the trailer, taking the torsional load off the transom. Well, Yamaha, as far as any research I've done and can come up with so far, does not really require ANY support of their motors. And maybe it's really not needed. But, that motor of mine, if I recall, hovers close to 700 lbs. The power tilt and trim pivot point is the primary support for the total weight of that motor.

But, there's a break-over point. Tilted too far forward and you're not putting *revers* strain on that transom. Tilted not enough and, you're either putting strain on the power tilt ram or, if one choses, you can rest the weight of that motor on the power trim rams. I preferred not put that strain on either one. So, I fabricated that support so that it takes the weight (or part of it) at the base of the power trim rams and, the vertical pivot arm (for steering).

You mentioned some good points on stress points within that support. Those are four, stainless steel 10-24 x 2" screws. They are threaded directly into the second half plastic. I've got lots of experience in dealing with not only this type of situation but, also various types of plastic. In the original design, I did some searching for 2" thick HDPE and, yes you can buy it but, it's phenomenally expensive and, you have to buy normally what's called a 1/2 sheet, meaning 4' x 4'. Well, obviously, for a small motor support such as I was designing, a 4'x4' sheet of 2" thick HDPE was a zillion times overkill. So, I found a 12" x 18" x 1" cutting board on Amazon for $16 and free shipping. So, that was a no-brainer. The power trim rams are a hair over 11/16" in diameter. I figured I'd need a 3/4" hole just for clearance for each one.

Not to mention, I don't have the precise milling and drilling equipment to drill accurately placed 3/4" holes. That plastic cutting board is under 1" thick. So, a 3/4" hole doesn't leave much meat for support. Sooooo, this is why my design went with TWO identical pieces of plastic, screwed together. But, based on the fact that there is a lube zirk fitting in that vertical pivot arm (steering support) , very close to the contact point of the upper section of the support, I could not have double thickness all the way up. Soooo, I trimmed off a bit from one piece. The base is double thickness but the top, is single.

Single thickness of 1" piece is definitely enough for partial support of that motor. But, the thin walls of the drilled holes, were enough to force me to create double thickness, at least at that end. You're skeptical about the stress produced on those four stainless screws. I don't disagree with you. But, again, I've got lots of practice with this type of scenario. Based on design, frequency of use, limited travel distance(s) while that motor is supported, would lend that support to have a long useful life. I appreciate your input. Thank you.
Scott

Scott, thanks for taking the time to share your solution! Maybe you should be seeking a patent...

Michiman,
I most definitely appreciate your nice comment(s). However, there is already a support marketed that is that same design. I merely copied it for my application. Not to mention, at least on the Bennington forum, I've not seen any real desire or searching from members, for a motor support for this generation of Yamaha or Merc etc. So, this is just a piece of mind thing for me.
Scott