Outdrive hole cut with transom in boat

[sprintst]

Just checking to see if the outdrive hole can be cut with the transom installed in the boat...using the Mercruiser template and drilling fixture.

I have an aluminum hulled Starcraft Holiday with Mercruiser 140 and Mercruiser I Drive.

My original thinking was to drop it into place and mark the opening and bolt holes, pull the transom, cut the outdrive hole and drill the bolt holes.

The mechanic who is bolting the engine in wants me not to cut the opening and bolt the transom in place. I'm having a hard time picturing how he can do it. I know I can find a hole in the dark but I'm wondering how he can line this hole up from the inside when the transom is back in.

Just wondering what you pros figure as I'm not getting the best vibe from this guy.

 

[starsnstripers]

Re: Outdrive hole cut with transom in boat

I did my 21.5'er and all i read was that you use the factory measurements from the bottom of the hull to the bottom of the cutout to get the right height for the drive to be in the right spot regaurding the plates/fins on the drive. Then you mount the gimble assly. and mount engine to match where the drive is. There's a specified height the drive needs to be in conjunction with the hull bottom.

 

[achris]

Re: Outdrive hole cut with transom in boat

Just checking to see if the outdrive hole can be cut with the transom installed in the boat...using the Mercruiser template and drilling fixture.

No.... You use the transom drilling fixture to drill the holes AND mark the cutout.

I have an aluminum hulled Starcraft Holiday with Mercruiser 140 and Mercruiser I Drive.

If you're installing a new Mercruiser you should only have to drill 2 new holes at the top of the cut-out.

My original thinking was to drop it into place and mark the opening and bolt holes, pull the transom, cut the outdrive hole and drill the bolt holes.

This doesn't make sense... The rear of the engine sits on the inner transom plate. You can't put the engine in without the transom plate bolted up.

The mechanic who is bolting the engine in wants me not to cut the opening and bolt the transom in place. I'm having a hard time picturing how he can do it.

Can't be done.... Transom plate MUST on on first.... No another way (as my wife would say )

Just wondering what you pros figure as I'm not getting the best vibe from this guy.

Ask your mechanic how many Mercruisers he has installed.... I bet it's a nice round number.... '0'

Chris......

 

[sprintst]

Re: Outdrive hole cut with transom in boat

I was just wondering how he could possibly line everything up with the whole 2" epoxied plywood already all bolted in.

I was thinking he had a way to drill a couple of holes from the outside to help line up the template from the inside of the boat. He would then take the template and fixture and do his drilling and marking to mark the outdrive opening from the inside of the boat. He would then cut the outdrive opening keeping it square somehow. He would then bolt on the transom plate and keep going.

 

[starsnstripers]

Re: Outdrive hole cut with transom in boat

If your going to do it yourself i have the specs. If someone else is going to do it for you then they should already know or have the specs and know how it's done. good luck!

 

[achris]

Re: Outdrive hole cut with transom in boat

I was just wondering how he could possibly line everything up with the whole 2" epoxied plywood already all bolted in....

A single hole is drilled, from the outside, through the ali and the 2" plywood, at the centreline of the engine, at the right height (see instructions that came with the engine for calculating the correct height). The transom drilling fixture is then bolted to the outside of the transom with that single hole and the rest of the holes are drilled. The cutout is marked up and the steering arm clearance holes are drilled (at 60 degrees). Template is removed, hole edges should be glassed, and the gimbal housing and inner transom plate are mounted up.... Then, and only then, can the engine be lowered into the boat.

 

[fishrdan]

Re: Outdrive hole cut with transom in boat

I'm a bit confused, you all ready have the template on the back of your boat, the aluminum hull skin. Since you are going back with the same engine/drive it should all line up with the existing cutout and holes in the aluminum skin.

As I see it, the mechanic wants you to bolt in the new plywood transom so he can align the jig with your existing holes, drill it 100% square, and then make the cut out.

Unless I'm missing something...

 

[achris]

Re: Outdrive hole cut with transom in boat

I'm a bit confused, you all ready have the template on the back of your boat, the aluminum hull skin. Since you are going back with the same engine/drive it should all line up with the existing cutout and holes in the aluminum skin.

As I see it, the mechanic wants you to bolt in the new plywood transom so he can align the jig with your existing holes, drill it 100% square, and then make the cut out.

Unless I'm missing something...

Ahhh!!! The picture gets murkier... I thought he'd pulled out an older 140 and was putting something newer in, like a Gen II. I'm still trying to work out how you remove the transom from the boat so you can cut the hole in it

Mr 'sprintst' Please explain exactly what's happening so we are all talking about the same thing.... It appears some of us have missed the whole story...

Chris........

 

[Bondo]

Re: Outdrive hole cut with transom in boat

I was thinking he had a way to drill a couple of holes from the outside to help line up the template from the inside of the boat. He would then take the template and fixture and do his drilling and marking to mark the outdrive opening from the inside of the boat. He would then cut the outdrive opening keeping it square somehow. He would then bolt on the transom plate and keep going.

Ayuh,... 99% of the cuttin',+ drillin' is done from Outside the barge...

Install the plywood 1st,... Then drill,+ cut...
Then install the transom assembley...
Then hang the motor off an alignment bar to find the Exact spot for the foreward motor mounts...
Then bolt it all together...

That's How I've been doin' it anyways....

 

[sprintst]

Re: Outdrive hole cut with transom in boat

It's the same 140 going back in after a rebuild.

The aluminum skin on the stern does give the exact opening he would have to cut.

My question in a round of about way was to see if he can possibly do the cutting with the transom already bolted in. I"d prefer that he didn't.

I don't want to 5200 any of the bolts or pop rivet the alum top cap back on if he is just going to pull the tramsom out to cut it on a nice flat table.

I also don't like driving it over there without most of those bolts back in as the stern area of the hull will flex without support.

Sorry about the confusion. I was looking fo feedback to see if I should get it done somewhere else if depending on the whole "cut in place or out of the boat" thing.

I respect the opinions of you salty sailors as any layman is liable to to come up with all kinds of crazy solutions when there is only one right way to do something.

 

[Bondo]

Re: Outdrive hole cut with transom in boat

My question in a round of about way was to see if he can possibly do the cutting with the transom already bolted in. I"d prefer that he didn't.

Ayuh,... Prefered or Not,... That Is in fact How it's done....

 

[sprintst]

Re: Outdrive hole cut with transom in boat

There you go. See how easy that was

 

[achris]

Re: Outdrive hole cut with transom in boat

Bond-o,

I think this guy is calling the transom plates, the 'transom', which, as you and I know, is actually the back of the boat.

sprintst,

Please get your terminology right, that's what is causing the confusion here....

Transom - Flat rear part of the boat, usually has an engine bolted to it, or a Stern drive mounted to it. In an ali boat will have a reinforcing piece (usually marine ply) secured to it....

Inner transom plate - Flat plate, with things like rear engine mountings and steering cable bolted to it. In older engines it may also have the trim pump and trim sender mounted to it.

Gimbal housing - (also can be called outer transom plate). Bolts to the outside to the transom. Houses the gimbal bearing, bellhousing and is responsible for turning the drive unit when the steering arm is moved. Also drive unit mounts to this....


To the original post.... The cutting out and drilling is done with the marine ply in the boat, secured and fixed. A drilling template is fastened to the outside of the back of the boat (this is the 'transom') in the correct place, and the holes are drilled and the cutout marked. NOTHING ELSE SHOULD BE ON/IN THE BOAT, no engine, no transom plates, nothing.

As you already have a cutout and the hole positions in the transom (the ali section of the back of the boat) then you don't need the drilling template. Just secure the ply to the inside of the transom, mark it up and cut it... Couldn't be easier. Just remember to angle the holesaw for the steering arm cutouts at 60 degrees, or you'll not have enough room to swing the steering arm.

Hope this helps....

 

[sprintst]

Re: Outdrive hole cut with transom in boat

Bond-o,

I think this guy is calling the transom plates, the 'transom', which, as you and I know, is actually the back of the boat.

sprintst,

Please get your terminology right, that's what is causing the confusion here....

Transom - Flat rear part of the boat, usually has an engine bolted to it, or a Stern drive mounted to it. In an ali boat will have a reinforcing piece (usually marine ply) secured to it....

Inner transom plate - Flat plate, with things like rear engine mountings and steering cable bolted to it. In older engines it may also have the trim pump and trim sender mounted to it.

Gimbal housing - (also can be called outer transom plate). Bolts to the outside to the transom. Houses the gimbal bearing, bellhousing and is responsible for turning the drive unit when the steering arm is moved. Also drive unit mounts to this....


To the original post.... The cutting out and drilling is done with the marine ply in the boat, secured and fixed. A drilling template is fastened to the outside of the back of the boat (this is the 'transom') in the correct place, and the holes are drilled and the cutout marked. NOTHING ELSE SHOULD BE ON/IN THE BOAT, no engine, no transom plates, nothing.

As you already have a cutout and the hole positions in the transom (the ali section of the back of the boat) then you don't need the drilling template. Just secure the ply to the inside of the transom, mark it up and cut it... Couldn't be easier. Just remember to angle the holesaw for the steering arm cutouts at 60 degrees, or you'll not have enough room to swing the steering arm.

Hope this helps....

Nope... I got the terminology right. Transom...the whole sheet of 2 inch sheet of plywood. Bolt it in to aluminum skin. Mark it and drill holes with template. Pull sheet to cut it or somehow cut it while still bolted to alum skin.

 

[wvmedic]

Re: Outdrive hole cut with transom in boat

Sprintst I agree, you're terminology was correct. I think someone might have misread you're post. I understood exactly what you were asking, and understand why I believe.

In the resto threads it shows folks cutting everything outside of the boat, glassing and then putting the transom back in bolting it up etc. I don't remember if you're old transom could be used as a template or not, if it can be I don't see why it wouldn't work.
Maybe Bond-o will chime in on using the old transom as a template to cut the new one.

Jeff

 

[achris]

Re: Outdrive hole cut with transom in boat

Nope... I got the terminology right. Transom...the whole sheet of 2 inch sheet of plywood. Bolt it in to aluminum skin. Mark it and drill holes with template. Pull sheet to cut it or somehow cut it while still bolted to alum skin.

My bad... Just not used to boats with 'removable transoms'.... Initially I thought you were talking about the engine being put in and the hole marked up with the engine in place....

Just that once a boat is built the transom is part of it, can't be removed and cut up....

Sorry....

Given the case now, I don't see a problem either way, as long as it's cut right.... It would depend on the tools available as to which method would be easier...


Chris.........

 

[sprintst]

Re: Outdrive hole cut with transom in boat

You glass types definately have no choice there. Your transom is removable too...just in a lot smaller pieces

Part of it is asking how you guys do it in place. so that it doesn't end up getting cut cockeyed.

 

[Bondo]

Re: Outdrive hole cut with transom in boat

Part of it is asking how you guys do it in place. so that it doesn't end up getting cut cockeyed.

Ayuh,... I've done a dozen or so transoms in both glass,+ metal boats...
Nope, I don't use a mercruiser drilling jig, I use the old hole in the glass or tin,...
If doing a virgin transom, I have an old cut-out salvaged from an old junk tin boat to do my lay-out with...

To be absolutely honest,... I can't imagine trying to get the angles anywhere near Right drilling on a bench, with the hull out in the barn....
Where as, standing at the back of the hull,..
It's Easy to guesstimate the angles for the studs,+ the big key-hole is a matter of trimming back to get clearances...

so that it doesn't end up getting cut cockeyed.

You'll be drilling through the existing holes in the tin,... That's How...

 

[achris]

Re: Outdrive hole cut with transom in boat

If you have a drill press big enough you'll get the holes very square.... For the keyhole shaped cutout, I'd use a good jigsaw...

 

[sprintst]

Re: Outdrive hole cut with transom in boat

One last question on this thread.

Just checking to see if this 1/2 piece of plywood used to build the transom thickness has to be the same size or can be slightly larger. Not thickness wise but length and width. I want to use a larger square around the opening and to add some thickness around where my kicker bracket is but that's another story.

It looks like many people duplicate the dimensions of this piece to the factory shape but was wondering if there was any reason to it. I'm concerned for clearance issues since one this piece is epoxied in it's not going anywhere.