installing an outboard auxiliary onto my 23ft cuddy

[SeaLord]

I roam the ocean with my glastron 229 gs volvo penta 5.7 gl-a plus sx M.
Nothing to complain so far but I would certainly feel much better with an additional outboard engine since the all family is coming with me, just in case.
Eventually I bought a tohatsu 9.8hp 4 strokes long shaft (25in) weighing 98lbs. I have also ordered a bracket from seasense supporting the weight and the outboard power.
MOTOR BRACKET

Since my boat hull sports a swimming platform by design I discovered that there is not a smooth vertical part on my stern to fix that bracket. Everything tends to round so the flat plate is not really a match.
I thought I might have installed the plate on the floor of the swimming platform with some modification: making sure that another plate is installed on the bottom side of the platform so the swimming platform is sandwiched by the 2 plates with the help of the relevant bolts.
I may then change the side of the plastic support, release completely the locking mechanism so the device becomes pretty much a straight arm with a supporting plastic pad at the end
Since it was not designed that way somebody may see immediately what may go wrong with my project.

Thank you

 

[Bob_VT]

Re: installing an outboard auxiliary onto my 23ft cuddy

Let me slide this to the restoration section. I would make a spacer that matches the contour of the hull from exterior plywood and I would fiberglass over the entire piece and gelcoat it to match the hull. Mount that pice and then mount the motor bracket.

I hope you get the idea from my poor drawing

 

[Bob_VT]

Re: installing an outboard auxiliary onto my 23ft cuddy

Once mounted you can tie in a steering link to your current outdrive but I would make that detachable

 

[SeaLord]

Re: installing an outboard auxiliary onto my 23ft cuddy

Thank you Bob
your suggestion has the advantage that is using the bracket exactly the way it was designed. But it is somewhat complicated especially knowing that the boat roams in Africa where material and workmanship is not that ready available. How do you imagine I tie a steering link to my sterndrive (volvo penta sx-m) ?

Have you given a thought to my approach ? this is basically transforming the bracket into a fix arm installed on and protruding from the swimming platform floor. With an extra SS plate on the bottom side of the swim platform floor would be very easy to do. Can you see what it may go wrong ?

 

[Bob_VT]

Re: installing an outboard auxiliary onto my 23ft cuddy

Yes, you could come off the top or the swim platform with a stainless steel plate and have the vertical portion made from stainless too. It would be similar to a massive L bracket but, I would still add connectors to the bottom of the bracket for the thrust pressure on the hull. I would also attach a piece of 3/4" plywood (exterior or sealed with fiberglass and resin) to the bracket so the seassense has a proper mounting surface.

The bracing under the vertical portion can be 2 bolts installed with sleeves to take up the pressure.

 

[SeaLord]

Re: installing an outboard auxiliary onto my 23ft cuddy

I cannot tell you enough how grateful I am for you having this discussion with me.
I understand I was not clear enough about my sandwich design so I join a draw for your comments.
The original seasense bracket will be reduced to a fix arm supported by 2 SS plates (the original seasense and 1 custom built) sandwiching the swimming platform.
The engine (25 inch shaft) would tilt up and down position by its own standard mechanism.

Even with the 2 ss plates I cannot tell for sure if the arms and bracket would be strong enough to resist:
1 the propulsion force (glastron 229gs displacement 3600 lb)
2 the gravity force multiplied by the leverage the extended arm provides.
what do you think ?

 

[Bondo]

Re: installing an outboard auxiliary onto my 23ft cuddy

I cannot tell you enough how grateful I am for you having this discussion with me.
I understand I was not clear enough about my sandwich design so I join a draw for your comments.
The original seasense bracket will be reduced to a fix arm supported by 2 SS plates (the original seasense and 1 custom built) sandwiching the swimming platform.
The engine (25 inch shaft) would tilt up and down position by its own standard mechanism.

Even with the 2 ss plates I cannot tell for sure if the arms and bracket would be strong enough to resist:
1 the propulsion force (glastron 229gs displacement 3600 lb)
2 the gravity force multiplied by the leverage the extended arm provides.
what do you think ?
View attachment 217662

Ayuh,... Welcome Aboard,.... I googled yer hull to see what the swim platform looks like,...

If it's like this 1 I found,... Ya, I think yer Plan oughta work with a 10 hp outboard,...

 

[SeaLord]

Re: installing an outboard auxiliary onto my 23ft cuddy

Thank you for welcoming and for retrieving my model picture. I realize I should have posted it at first.
Hope I am going to receive several more comfort.