Motor mounting question

[chrizzo]

I have a 1990 Nitro Bass boat that I'm going to be mounting a 78 Mercury V6 outboard on. The mounting bracket has a more narrow bolt pattern than what my transom will accomodate so I'll have to plug the existing holes and drill new ones. The bracket is also deeper than the stock one was, so the bottom hangs down about an inch or so from the bottom of the transom. I've tried to attach a couple pics, hopefully it works.

As you can (hopefully) see, the transom steps down a couple of times before it reaches the bottom of the boat. The bracket will hang down about an inch below the first step down. Is this a problem?

 

[DJ]

Re: Motor mounting question

One option would be to mount the engine to a jackplate. A manual jack plate is not that expensive.

That would eliminate drilling new holes, in the boat and would probably lift the engine enough to avoid the bracket hanging down into the path of spray.

 

[chrizzo]

Re: Motor mounting question

I'm not too familiar with those, but I just looked up a few on the cabela's site.

So if I got one where the holes lined up to mount the jack plate to the transom, how would the holes work where the motor mounts to the jack plate? Would I have to drill new holes in the plate?

 

[DJ]

Re: Motor mounting question

I'm not too familiar with those, but I just looked up a few on the cabela's site.

So if I got one where the holes lined up to mount the jack plate to the transom, how would the holes work where the motor mounts to the jack plate? Would I have to drill new holes in the plate?

Yes. more than likely. Many plates come with a variety of mounting choices. The holes may already be there.

The only downside is that your steering cable may not be long enough. That will depend on whether or not your steering cable has any slack and the "set back" of the plate.

 

[chrizzo]

Re: Motor mounting question

So the idea then is that its easier to drill new holes in the jack plate, rather than drill new holes in the transom while also having to plug the old ones, and in additionto that I'll be able to raise the motor a bit higher to solve my other problem... makes sense.

And yeah, I'll have to double check the steering cables if I go this route. Thanks for the help.

 

[tashasdaddy]

Re: Motor mounting question

iboats marine store has a great selection, we try to support the benefactor of this free forum, by patronizing the store when possible.

http://www.iboats.com/Marine_Store/dm/keywords.jack plates--submit.Search--submit.x.3--submit.y.7

 

[Ed R]

Re: Motor mounting question

You have one of the first merc V6 models, it has old style bolt mount up in witch the bottom bolts are used for the power trim hoses. As per picture, they are above the {step on your transom.] it will be fine. You need to fill the existing holes. I have not seen one of those motors in years!!! GO for it, eddie.

 

[chrizzo]

Re: Motor mounting question

Oh, ok. I found this forum by a google search, didn't even realize there was a store associated with it. The only problem I see with some of those pictures, for instance the fixed plate, is that it doesn't look like they will accomodate the drilling of a more narrow pattern that my motor (a '78) will require.

Has anyone here mounted an older Merc like mine to one of these modern jack plates?

 

[chrizzo]

Re: Motor mounting question

You have one of the first merc V6 models, it has old style bolt mount up in witch the bottom bolts are used for the power trim hoses. As per picture, they are above the {step on your transom.] it will be fine. You need to fill the existing holes. I have not seen one of those motors in years!!! GO for it, eddie.

Totally forgot about the trim hoses in the lower bolts. So a jack plate probably won't be the way to go. I guess I'll just leave it where it is, and drill new holes. Thanks again for all the help.

 

[Ed R]

Re: Motor mounting question

Hey, don't get discouraged, that motor is great. If you want to put on a jack plate, you must drill new mounting holes as well. I don't think the old template is still available anymore but, center motor [measuring carefully] and drill holes, transom or jackplate!

 

[fdmsiv]

Re: Motor mounting question

I would do the following:

Get some epoxy and wood flour (fine saw dust can be substituted) and quality packing tape.

Mark the holes for the bolt pattern and remove engine.

Drill oversized holes for the new bolts ie, 1/2 bolts, 3/4 hole

On the outside of the transom, put a piece of tape over each hole. Make sure you get the air from under tape around the holes.

On the inside of the transom you want to use the tape to make a funnel with the openning at the top. Take a second piece and seal off the bottom of the V shaped piece. This is hard to describe, but the idea is this.

Epoxy will not stick to the packing tape. With the outside taped and the inside tape funnels formed, you slowly pour the epoxy into the funnels and let it fill the hole. There will be excess epoxy left in the funnel that will dry, but you can cut and that later.

Once the epoxy has set, redrill the correct size holes and you are good to go.

 

[chrizzo]

Re: Motor mounting question

Ok I think I'm following the process, but I'm not sure I get why... What you're describing is a process to drill the new holes in the transom, but why do it the way you describe as opposed to just drilling the correct size holes, sliding the bolts through, and using some sealant?

That's how I envisioned doing it, but I've never done anything like this before.

Thanks for the help,

Chris

 

[fdmsiv]

Re: Motor mounting question

The epoxy route ensures that the transom is sealed. Don't get me wrong, you can drill the correct size hole and use sealant, but you run the risk of letting water get to the core of the transom. Granted this doesn't happen overnight, but it eventually will happen.

 

[chrizzo]

Re: Motor mounting question

Got it. Totally makes sense now. Thanks for the info.