Glastron Surface drive

[CharlieN]

I have been picking away at this, just not taking the time to post anything.
This photo shows what the water level INSIDE the hull was for some period of time.
Surprisingly the stringers are good judging by core drillings I have taken.
The small areas of wood on the transom are 1/2 plywood and need replacing.
I intend to keep the flotation foam but the outside thin ply will be replaced, probably just wrapped with FG.
Still more to learn.

[CharlieN]

I actually have been busy working on this, I really have.
A fair bit of detail work on mounting the outdrive, spending time locating the transmission. Still a bit flummoxed just what height the transmission should be. When I get the trans at a height the output joint looks just right, it looks like it lacks trim up. The shaft is pretty close to being inline with the hull pad. It might be right, might be wrong.
I can lower the transmission a bit if needed and might build this out to allow for the adjustment in the future as the sea trials commence.
I dug forward under the front deck and removed the aftermarket gas tank, a commercial plastic 24 gal tank.
Just imaging a 455 Oldsmobile at cruise power, what would they be, 10-12 GPH. No playing all day with this one.
My 87 CVX 20 outboard has a 32 gal aluminum tank, quite generous for the 225 Yamaha.
I have been thinking of building underfloor tanks, plural since I intend to keep the center stringer.
I have 6 to 7 feet length with 20ish with, minus the 1.5 center stringer. Might be the right thing to do.
That should keep an alloy LS 6.2 happy for hours. I estimate cruise consumption to be half what the Olds/ Berkley drive would suck down.

I also removed the instrument panel and all wiring to the back of the hull, quite a tangled rats nest.
Photos next time, I want to cook dinner now.

[CharlieN]

I still have water drooling out. These pics were just taken this morning, it was for the most part dry late yesterday. The flotation foam goes all the way back in the hull extensions which I intend to stay in place and I expect will be dribbling most all summer. But I am getting closer to understanding what needs rework and just how to carry the new loads into the hull.
This will involve determining how much structure to cut back and scarf in new structure. My test drillings are not finding soft or wet wood elsewhere. The transom will be getting a small area of a composite core down low and metal structure to carry loads forward.

[CharlieN]

One of my next tasks will be closing off where I cut out the pump inlet. This is just flat pad about 10" wide. I will be molding in a cooling water inlet up and through the side wall of the removed tunnel. Possibly incorporate a water strainer as well but that might not be practical in the cramped location next to the transmission and under the long tube headers. There will also be a few structural tubes from the upper mount of the outdrive forward to the stringer, transmission mounts.

[CharlieN]

Cooling inlet,
I found this stainless tube on Ebay that I think is just right. It is 1" ID with a 1" NPT tread that I will install a ball valve into. The valve I have ordered has a 1" PEX outlet that I expect will feed a strainer. All of this is tucked down low under the transmission mount with long tube headers above. Not sure what I will have for room but I fancy the idea of the sea strainer in front of the engine.
This tube of all things is a performance exhaust pipe for a 9 to 13HP utility engine.

[CharlieN]

Over the past few weeks I have been figuring out some details, Following the documents that came with the drive it appeared the transmission needed to be raised up a bit over 1 1/2". This makes some aspects easier. As such I chose to raise the drive up by altering the mounts rather that utilizing a spacer to lift the brackets.
Here is the transmission sitting where it appears it needs to be,




The yellow strap is needed at this time since the transmission now floats on the soft mounts and will not be stable until the engine is added into the equation.

And two shots of the reworked brackets, the bracing is not complete, there will be an outer support welded in.

[CharlieN]

I just spent a few hours fixing quite a few broken links to my photos. If I recall I maxed out my Imjur account and did not recognize what files were in use. I think I dumped many of the files used on this site. I think I have them fixed. Now we see if the account is maxed out again, I take away cat pictures next time.

[skialot2]

This is an awesome project. looks like a lot of work. But work is not really work if you are enjoying it. Good luck with it. I will be following. I believe you said it uses a 1 1/2" propshaft. Could you have that machined to a standard Mercury spline? That would open up a good selection of surface running props.

[aj06bolt12r]

Over the past few weeks I have been figuring out some details, Following the documents that came with the drive it appeared the transmission needed to be raised up a bit over 1 1/2". This makes some aspects easier. As such I chose to raise the drive up by altering the mounts rather that utilizing a spacer to lift the brackets.
Here is the transmission sitting where it appears it needs to be,




The yellow strap is needed at this time since the transmission now floats on the soft mounts and will not be stable until the engine is added into the equation.

And two shots of the reworked brackets, the bracing is not complete, there will be an outer support welded in.

Keep cranking brother.. This is a cool project, enjoying following along!

[CharlieN]

I believe you said it uses a 1 1/2" propshaft. Could you have that machined to a standard Mercury spline? That would open up a good selection of surface running props.

1 1/4 shaft with flats to drive the prop.
I have recently been in contact with a few guys that have, or had this drive , most interesting has been the builder of the Yellow boat that has been my inspiration for this project.
He ran a built 406 SB, probably 100HP or so more than I expect to have, his had a 28P, he blew into the triple digits real quick, couldn't say how fast it topped at, no GPS and no desire to look down. He feels he never did actually top it out.

My prop is stamped 33.

[CharlieN]

Water pickup, revisited, I want to get the inlet plumbing up into site and in reach. Also up where I can install a serviceable sea strainer should I choose to. Instead of running low inside the stringer I bored a hole through allowing the hard line to get over to the side wall of the flotation box. I then added a 1 1/4 ball valve right at the entrance bulkhead. It has been a few variations leading up to this, I think I like it. I am sure it will change though as I go forward.

[CharlieN]

The images above were not viewable to me as a direct upload so I am linking to Imgur which might not be right for others.

[CharlieN]

Steering, Over the past month I have been plumbing the steering, I mounted the helm back in May


This might be an oddity that is important to me with 50 years of performance and competition driving and flying it is important that the steering wheel, or helm in this case, the spokes need to be level. So in my boats I install a valve under the panel that allows the wheel to be rotated without moving the outboard or in this case rudders, I can open this while running as well.


From there back the tubes are straight forward with bulkhead fittings through the transom and hoses back from there.