Aerotec transom Mod

[neil h]

Have you made any splash back mods Neil, or just trying the longshaft as a different engine?

No mods done yet Martin. I want to make some kind of plate, that will allow me to raise the OB 2-3" for the shortshaft Tohatsu, or about 5-8" for the longshaft Suzuki 15.
I definitely feel it needs more power, and since I have the 15 in ls guise, I need to think how to do it. Also have a 25hp ls Yammie 2/, that I need to get running again.

I want to see what happens with modding to ls before going further, so thinking just a simple plate both sides of transom with an infill for the minute.

Might even go out and get me some ply and varnish today.

The transom is 30mm thick. The outboard clamp opens to 55mm on the totatsu and about 60mm on the Suzi. So, I am thinking to get some 10mm ply, cut a front plate and a back plate, and then make some filer pieces to sandwich between the two plates above the transom.
I'll probably make 6 filler pieces, two for the Tohatsu to give the option of a 2" or 3" raise, and 4 for the Suzi to give the option of a 5", 6", 7" or 8" raise.

The two outer plates will be bolted through the filler at the top to hold all that rigid.

The outer plates will be drilled in multiple heights so they can be bolted through the transom in different places.
I will only two holes through the transom, to start with anyway, near to where the bottom of the plate would be in the highest setting. A mentioned above, the top section will be bolted together, and sit on top of original transom, so it's only really to hold it all securely in place.

So that's what I was planning to try as a starter to see what happens with each engine. If it seems to be working, I can then consider making a wider infill for the top of the transom to go the entire width.
Wil probably be working on it over xmas hols, and hope to get it done in time for testing in Poole, if not before.

[Martin]

I hope you get it sorted Neil.
Stray has a bombard, perhaps he can advise any mod he's had to do, if any .... to stop the waterfall on the bombard??

[Paul]

Neil

I have a metal bracket I made up for just this experiment that you're welcome to have
I've put on some measurements for you but as you can see that it's a clamp so it allows you to insert packers on the transom top and under the OB bracket.
Here's some photos to give you a better idea of it

Transom Lifter1

Transom Lifter2

Transom Lifter3

Let me know if it's of any use to you

Paul

[neil h]

ooh... thanks, that could be handy, if only to see if it helps matters with the Tohatsu.
Thanks

Just need to work out a good time for collection....

[Martin]

Is that the bracket you made to use the longshaft Honda outboard Paul

[Stray]

Stray has a bombard, perhaps he can advise any mod he's had to do, if any

I didn't make any permanent mods, I tried the outboard higher up using pieces of wood, but it didn't make much difference. To be honest, the water only sprays up the back, it doesn't come into the boat that much, it's more of an annoyance.

Anyway, I've solved the problem, I'm selling the Bombard in the spring.

[neil h]

Lucky you. Mine sprays up the back and comes over a bit at the sides. But it rushes up the back behind the outboard saddle and comes in over the outboard saddle flooding the boat with a waterfall tap effect. Anything over about 10kn is impossible to maintain as the boat fills with water.

Thats with a 1" shim on top of transom. Removing it made it worse. So hopefully raising it will help even more.

[PeterM]

I ended up with about 1 1/2 inches on both of mine Neil ( the pic is a bit less and still let some in - this is my Round Portsmouth 2015 boat) - running 20 & 25 hp Merc on both. With the 25 without the raise it was like you say a six inch wide waterfall under the saddle !

The water comes together again quickly either side of the ' Y' at the rear of the hull - so hits the square/ not streamlined leg of the OB - A LS extends down so far you''ll have to go a long way up to avoid this .

Look out for a winter 25hp short shaft and go for it ! ( found one on my work PC - its amazing what I have stored and didn't even know about ! )

I'll see if I Can find pics of the two extensions on the ones I've had/ used.

Pete

[neil h]

Interesting. Thanks Pete. I have Pauls welded extension gizmo to try at some point with the tohatsu ss.

Tempted to look out for a 25 ss but cant justify another ob if i can do without.
I already have a 2 ls a 9.8ss a 15 ls a 25 ls a 175 xls in pieces in the outhouse a 90 ls on the Ring and the 200 on the Shakespeare.

Need to sell the Ring for a start!

[neil h]

I tried to post here yesterday but my ip address was blocked.

Paul's mod was just the job. Waterfall gone both one and two up. (65mm of lift). Just a tiny splashing now but no volume to it. Cavitates a little bit but can live with that.

So need to measure up and make a permanent solution up, and give Paul his bracket back in case others need to borrow it.

Thanks again Paul.