Avon SR4 Transom

[andyace]

HI

Is there anyone in the Poole area that can replace my Transom? i went to replace the tired mariner 2stroke with a 40hp Honda 4stroke, when i got the mariner off i found the transom is soggy left to right, top and probably to bottom.....rest of the boat is fine fitted a new console so don't want to give up on it now

Thanks

Andy

[andyace]

So i cut out the inner laminate to floor level unglue the tubes from the ends, chisel out the ply, make a new one with 12+18mm ply bonded together
and insert it, get my GRP expert to re-glass it,re-attach tubes, then paint and then attach engine????

[whisper]

I can do it if you bring it up to me in Wootton Bassett or Swanwick

[andyace]

HI
Thanks if i cant get anyone in Poole or nearby to take a look i may take you up on that.

Andy

[il corvo]

Originally Posted by andyace

So i cut out the inner laminate to floor level unglue the tubes from the ends, chisel out the ply, make a new one with 12+18mm ply bonded together
and insert it, get my GRP expert to re-glass it,re-attach tubes, then paint and then attach engine????

thats exactly what my father did on an early sr4 then plated inside and out with 3mm ally plate top to bottom and full width of the transom then through bolted and sealed with 3 floor to transom braces. total over kill but there was no flex at all. fitted a 75hp merc 2 stroke. thing f**king flew (in the very early 90's this was). safety meant less then.

[nugent]

Done a few of these now,
Not worth making do, the wood will b knackered trust me look at these two I did this year one had 18 mm ply the other was going 4 stroke so I put double layer of bonded ply to be sure


Whisper will look after you worth the trip for quality workmanship

[whackywoody]

75 hp (2 stroke) on an Sr4! I like the sound of that how fast is fast though?

[andyace]

What ply?
thinking hardwood marine ply but any particular brand/type?

[il corvo]

Originally Posted by whackywoody

75 hp (2 stroke) on an Sr4! I like the sound of that how fast is fast though?

well, it had a pitot tube speedo so not really accurate (no hand held gps then) and that would read 54kts, it would out drag the red funnel hydrofoils and the 1st gen catamarans they used buy quite a margin in the right sea conditions. sat quite stern heavy but could pull two monoskiers up no worries.

kept up with a Fletcher arrowbeau GTS no problem.

[matt h]

Whisper will look after you worth the trip for quality workmanship

second that. or buy a nice SR4 off him instead

[andyace]

Thanks to the informative and inspiring information on Rib.Net i have started doing this Transom Replacement (Comments very welcome)

You can see how rotten the core is, I used a hair dryer (rather than a hot air gun...) to release the glue bonding the tube the the sides of the transom, thought i would have less chance of setting everything on fire



Chipping the core out and blunting all my chisels



All the wood is out down to deck level where it seems dry and strong



New transom cut from 18mm 8 core marine ply, the gaps at one end are to give it wriggle room to slide in, ill epoxy fill these.



Now to Epoxy prime it and set it in with more epoxy. need to go and get 10 clamps, advice is not o over clamp and squeeze all the epoxy out.

[andyace]

Cleaned up the surfaces

[whisper]

Well done you!!

[ribraff]

I'm sorry but I don't believe that just replacing the transom to deck level is the correct procedure, the transom relies on one single structure of wood for strength, in this case (SR4) the transom continues to the keel, just replacing the wood to deck level is building in weakness.

[whisper]

Hold on he hasn't finished dude, I'm sure he'll keep going

[ShinyShoe]

Originally Posted by whisper

Hold on he hasn't finished dude, I'm sure he'll keep going

But he's already fitting the new Ply from deck level and above having said the bit below is sound. I think RibRaff is right to shout now rather than when he's finished and is applying the final coat of varnish... ...No? Now how much flex happens through the bottom part of the transom I have no idea... but if it was me I'd want someone to make me think and at the very least then I might beef up the knees to the deck as the top transom wont be directly secured to the keel.

[gtflash]

Where's the knees? When I did my transom the wood only went down 2/3rds then it was sold glass. However if wood had travelled south anymore then the water most likely would have also. Gravity sucks.

[ShinyShoe]

Originally Posted by gtflash

Where's the knees?

Looks like it has s/s ones rather than glassed in ones. Glassed would reduce flexing better which if there is concern about the bottom transom join I'd think would be a better solution?

Originally Posted by andyace

Attachment 107938

[andyace]

thanks for these comments
i have put a couple of test holes below the deck in the gap between the laminate and the wood only continues another 3cm.i would have to destroy a lot more to get this last 3 cm out cleanly.
also there is a 5cm lip of the old inner laminate which is strong to bond to.
an epoxy bond between the new and existing wood would be pretty strong.
will put some knees in as per suggestion, makes sense too me, but what do i know

[andyace]

When i compare my floor with the below project photo it is different. i cut a hole in the floor centre to put a well in for a bilge pump, the flooding tube is directly under the floor with no space between, ie the floor is resting on the orange glass fibre pipe in the hull. on the below there is a much larger space and the transom goes right through to the hull.
there must be more than one hull design for the sr4's?
when i inspect into the gap in the bottom of the transom i have removed there doesn't seem to be a great deal of wood below the floor, and i cant find a picture of a similar project with the floor out to see what the original transom would have looked like.