Avon SR4 Transom

[ribraff]

This is one I did a while back, two complete pieces of 18mm ply bonded together with a piece of the rear deck replaced so the the knees are glassed in all the way down to the inside of the hull.

[1eyedjim]

Surely the transom doesn't go all the way to the keel as the thru hull hole depth is not the thickness of the transom so must finish higher.

That picture looks like he is blocking the they hull off which is why it goes so low

I have a pic of my transom in my Sparrowhawk and this doesn't go to the keel either

[andyace]

right ply is epoxied in, seems strong and without the glass on it does flex a little if you lean back really hard on it.

now to glass it with roving and epoxy but before i do....
with 18mm ply and a few layers of glass it will be as standard
should i laminate another 18mm ply in to the existing and to the floor? this will mean removing the rubber tube attachments and moving them down the tubes 18mm also the support tubes will be a bit higher unless i notch them in to the first sheet.

or shall i leave as standard layer the 18mm up with the glass and put a stainless cover over the top for rigidity
i have a 40hp 4stroke honda 95kg LShaft going on.

Advice much appreciated

Andy

[gtflash]

Not sure about the other bits, but if you are using epoxy, rovings are not the most ideal fabric. They are very heavy on resin, which is expensive when it is epoxy. If I use rovings I reckon I use 3 times the resin I do with bi axial cloth. Bi axial is far superior and stronger as the glass is not bent like woven rovings are because it is stitched instead. If you use epoxy which is my preference just use bi axial 45deg fabric. My transom had a total of 6 layers of alternating direction 450g on inside face plus the tabing but that was for a 250hp, and built to same thickness. Only mild issue is bi axial isn't great in corners so needs a fillet of filler at corners.

Also don't use csm with epoxy. Equally a waste of resin and not needed as the superior epoxy resin causes the inter layered bond (for want of a better word).

ps I am no expert

Originally Posted by andyace

right ply is epoxied in, seems strong and without the glass on it does flex a little if you lean back really hard on it.

now to glass it with roving and epoxy but before i do....
with 18mm ply and a few layers of glass it will be as standard
should i laminate another 18mm ply in to the existing and to the floor? this will mean removing the rubber tube attachments and moving them down the tubes 18mm also the support tubes will be a bit higher unless i notch them in to the first sheet.

or shall i leave as standard layer the 18mm up with the glass and put a stainless cover over the top for rigidity
i have a 40hp 4stroke honda 95kg LShaft going on.

Advice much appreciated

Andy

[mdearman]

I used 300 gsm bi axial underneath as it goes found corners, then 600 on top. No expert either! The biaxial matting distorts like crazy once you cut it so my top tip is make sure you mark all the key points on the cloth get them in the right place then then squidge the rest of it flat once it's on it has a lot of adjustment

[andyace]

Thanks for that
will get some biaxial today and do it over the weekend
might even get her back in the water before summer starts......
Andy

[mdearman]

That's what I thought, this time last year....

[gtflash]

Originally Posted by mdearman

That's what I thought, this time last year....

Mines 2 years

[andyace]

Finished the Transom Rebuild!!!

Wet the ply with epoxy, then with thickened epoxy spread with a grout spreader all over. used slow hardener with the epoxy.



Clamped and left for 48 hours. with 2 m12 bolts through where the engine will bolt on.
then beat off the 4b2 with a lump hammer (mental note use wax paper between if you ever do this again...)



8 layers of 300g woven roving, 1 2 then 3 inches into the deck over the top and all the way down to the keel on the back, fast hardening epoxy (20 minutes laying up time) left for 4 days to go off.



2mm thick 90cm wide 3" deep with internal gap of 1 1/4 inch stainless cap, engine top mount and struts bolted through with m12 bolts



mounted the engine



have now had 2 hours bumping around in chop to no ill effect,

thanks to all those who offered advice, cost me £150 saved me £600.

[gtflash]

Originally Posted by andyace

Finished the Transom Rebuild!!!

Wet the ply with epoxy, then with thickened epoxy spread with a grout spreader all over. used slow hardener with the epoxy.

Attachment 108542

Clamped and left for 48 hours. with 2 m12 bolts through where the engine will bolt on.
then beat off the 4b2 with a lump hammer (mental note use wax paper between if you ever do this again...)

Attachment 108543

8 layers of 300g woven roving, 1 2 then 3 inches into the deck over the top and all the way down to the keel on the back, fast hardening epoxy (20 minutes laying up time) left for 4 days to go off.

Attachment 108544

2mm thick 90cm wide 3" deep with internal gap of 1 1/4 inch stainless cap, engine top mount and struts bolted through with m12 bolts

Attachment 108545

mounted the engine

Attachment 108546

have now had 2 hours bumping around in chop to no ill effect,

thanks to all those who offered advice, cost me £150 saved me £600.

Good job. Well done.

[Tim in Yorkshire]

Looks tidy.