Bolting on a 50hp Evinrude

[ali'i]

Will be mounting an approx. 235lb, 2000, 50hp Evinrude on a 15" rebuilt transom, using 5" vertical extensions. There are 4 top holes on each side of the motor, with 2" between the top and bottom, so guessing it doesn't really matter which ones I use, but the bottom only has a 2"x 1/2" long vertical slot, not actual round holes, and if I want my cavitation plate even with the bottom of the keel, I can't place bottom bolts at the top of the slot, (8" below top hole) otherwise they line up with where the splashwell meets the transom. Is it okay to move the lower bolts to the bottom of the slot so I can put bolts so they go thru transom and come out under the splashwell? Or, should I mount the motor lower, so I can put bolts at top of bottom hole, but would also mean cavitation plate would be maybe 2" below keel. Thanks

 

[steelespike]

Re: Bolting on a 50hp Evinrude

You don't want the "antivent"(cavitation) plate" below the Keel.
Is it not possible to put the bolts where the splash well meets the transom?
why can't you bolt elsewhere in the slot?

 

[F_R]

Re: Bolting on a 50hp Evinrude

Isn't that what he is asking? If I read the question correctly, the bolts will be re-located further apart than spec'd. I see no problem with that.

 

[ali'i]

Re: Bolting on a 50hp Evinrude

if I drill thru transom at the top of lower slot, it will come out the other side exactly where the splashwell meets the transom, not a little below, not a little above, (slightly below level of the drain hole), which is of course at the bottom of splashwell, and I don't know if its okay to bolt elsewhere in the slot, that was my main question, wouldn't be a concern if it had 4 separate holes like the top ones, then I'd just use the bottom hole, but if bolt is at bottom of slot and not the top, will it still have the same holding strength as if it was just a 1/2" hole? it is after all, a 235lb motor.

 

[racerone]

Re: Bolting on a 50hp Evinrude

This is fairly simple.----------You drill through the top hole on the motor and the transom.-You drill at the top of the slot for those bottom bolts.-----If your installation is not quite right you can raise the motor with no more drilling required.

 

[oldboat1]

Re: Bolting on a 50hp Evinrude

couple of points or questions: I don't think measurement from (or to?) the bottom of the keel is what you are after. Measurement would be from the bottom of the boat (with a deep keel, for example, your motor would presumably be mounted too low if you measured from the bottom of the keel). 2 inches below the bottom of the boat would be a bit too low for the plate, IMHO. About an inch maximum is the rule of thumb. Also, I don't think putting mounting bolts below the splashwell is a problem, as long as the reinforcement for the new transom goes that low. If you would be going through only the skin of the boat down there, for example, that would probably not be strong enough. There is a lot of torque down there for a hole shot, or just running at speeds.

 

[hardwater fisherman]

Re: Bolting on a 50hp Evinrude

on my previous boat i had the same problem. im not sure if yours boat is fiberglass or tin. but what i did was cut out two holes in the splashwell with a hole saw. and after installing the bolts i glassed back in the pieces cut by the hole saw. there was two bumps in the splashwell but it still channeled the water to the drain.

 

[ali'i]

Re: Bolting on a 50hp Evinrude

Boat is early 1970's fiberglass runabout and was fully restored by previous owner, which included rebuilding the stock 15.5" transom, everything (almost) I read, and pictures I have seen, says cavitation plate should be even with the very bottom of the transom, so that is where I am measuring my 20" from. (See attatched pics) All I am trying to find out is, can the lower bolts be anywhere within that 2" slot, or MUST they be at the very top for maximum holding power, even though top bolts are in a 1/2" hole, and will probably take most of the weight, I am guessing they can be anywhere in the slot, otherwise they would have put individual 1/2" holes like the top, but I have guessed wrong before.

 

[oldboat1]

Re: Bolting on a 50hp Evinrude

think your location of the plate is right on (per diagrams). As a practical point, marking and then drilling in the middle of the slots makes sense if you have to predrill all the holes before mounting the motor. That gives you some room for error, but I'm not quite getting the configuration from your description. I can't address the engineering issue you raise with bolt placement -- don't believe (intuitively) there would be a functional difference where the bolt is placed within the slot, but I'm not an engineer (and haven't worked professionally on hulls or motor installation).

I've replaced two or three transoms on '60s and '70s hulls with some informal boatyard guidance, and have always been sure to place the new plywood (@1 1/2 inch thickness) down to the bottom of the hull. I would want to be sure that there is new wood down through the point where you will be drilling mounting holes, at a minimum. Ideally, the new wood should be all the way to the bottom of the boat to handle the motor's torque. You can drill some small test holes down there to see what you have (would do it from the inside so the test holes can be filled and patched without being seen).

 

[F_R]

Re: Bolting on a 50hp Evinrude

Fer gosh sakes. The factory drilling template gives options. Take your pick already.

 

[ali'i]

Re: Bolting on a 50hp Evinrude

Well excuse me, not everyone has access to a factory drilling template, and not everyone has had to drill mounting holes in a transom or has as much experience with boats as others, which is why we are on here asking questions. it was a simple question, can the lower bolts me mounted anywhere within the 2" slot or not.

 

[Bob_VT]

Re: Bolting on a 50hp Evinrude

Mounting template here http://forums.iboats.com/non-repair...tion-about-mounting-holes-transom-404847.html

 

[F_R]

Re: Bolting on a 50hp Evinrude

Hey ali'i, you're killing the messenger here. My frustration was with all the non-answers, not the question. Nevertheless, the paper template that Bob just posted should give the answer and clear up any frustration. You can put the lower holes wherever you have to or want to. The motor doesn't care.

BTW, I have mounted lots of motors where a single choice would have interfered with something inside the transom. That's exactly why they give an option.

 

[jbcurt00]

Re: Bolting on a 50hp Evinrude

Mounting template here http://forums.iboats.com/non-repair...tion-about-mounting-holes-transom-404847.html

Is it my computer or is the template image missing on that thread ^^^ Bob?

A 20" motor on a 15.5" rebuilt transom isn't straight forward, I'd like to see what these look like:

Will be mounting an approx. 235lb, 2000, 50hp Evinrude on a 15" rebuilt transom, using 5" vertical extensions.........

 

[boobie]

Re: Bolting on a 50hp Evinrude

A simple answer to your question. You can put the lower bolts any where you want to in the slot. But it may hamper raising or lowering the motor in the future.

 

[oldboat1]

Re: Bolting on a 50hp Evinrude

Make a template from cardboard or a scrap piece of panel, or something similar. See where the holes fit on the boat, and determine if you have the structural strength there. Talk to the guy who rebuilt the transom if you can, and find out what he did.