Right then boys this is the big one… Transom build time.

[mdt]

Sunday is earmarked as the day to build a 5.4 transom.

So the questions are.

1: will 3 sheets of 18mm marine ply bonded be enough?

2: how big should one make the knees?

3: any one got any other words of wisdom?

4: we are starting at 10am when should we open the first beer?

[willk]

Originally Posted by mdt

Sunday is earmarked as the day to build a 5.4 transom.

4: we are starting at 10am when should we open the first beer?

Strikes me you've already left it a bit late

[Bigmuz7]

I think you should put all your questions in reverse order .. she'll be a good un after that ......

ooh .. ok then .. how big is the motor ?

[JSP]

Sounds the kind of job that would take me 3 months. Keep us up to speed on it mate and take photos'!

[mdt]

Originally Posted by Bigmuz7

I think you should put all your questions in reverse order .. she'll be a good un after that ......

ooh .. ok then

Yes well the plan is to have the beer once we see the light at the end of the tunnel…

Originally Posted by Bigmuz7

.. how big is the motor ?

As you may have guessed I am wee way off sticking any engine on the back of this as yet, but I am looking to stick to the consensus that a 90hp is the best motor to a 5.4.

I have only driven 2 other 5.4’s one with a 60hp 2/ and the other with a 125hp 2/ the one with the 60 was the sweeter of the two but just a wee bit too slow. The 125 was not too slow. So I am working out that a 90 would be a fine compromise?

[mdt]

Originally Posted by JSP

Sounds the kind of job that would take me 3 months. Keep us up to speed on it mate and take photos'!

Discussed with brother in-law last night, as it is he who is helping out. And we recon. How hard can it be?

Buy ply wood (18mm)
Cut ply to the template (have got the template done already).
Bond together with epoxy resin

Lunch

Cut knees
Epoxy transom to boat
Fit knees

Job done. or am I missing a few steps?

aye fear not shall take photos... up to the point I epoxy the camera to my hand

[GBR1]

Originally Posted by mdt

Discussed with brother in-law last night, as it is he who is helping out. And we recon. How hard can it be?

Buy ply wood (18mm)
Cut ply to the template (have got the template done already).
Bond together with epoxy resin

Hi mtd,

I would do this in a different order, the epoxy will take at least 12 hours to set, fast hardener will take around 4 hours before you can work on it but your bonding surface is pretty big for fast! I would by the ply on Saturday (if possible) and bond together, lots of G clamps and or weight and then leave over night. Try and keep it warm (not hot) and dry for this period. You then cut all three sheets bonded together on the Sunday morning.

The advantage being that not only can you have a beer on Sunday, you can also have a few after your work on Saturday!

[mdt]

Originally Posted by GBR1

Hi mtd,

I would do this in a different order, the epoxy will take at least 12 hours to set, fast hardener will take around 4 hours before you can work on it but your bonding surface is pretty big for fast! I would by the ply on Saturday (if possible) and bond together, lots of G clamps and or weight and then leave over night. Try and keep it warm (not hot) and dry for this period. You then cut all three sheets bonded together on the Sunday morning.

The advantage being that not only can you have a beer on Sunday, you can also have a few after your work on Saturday!

I was looking to cut the 3 sheets out first and then bond them together. As other wise I am going to have to cut out 54mm of ply in one hit. I have cut enough kitchen worktops in my time to know that if possible this should be avoided. I am being flippant about the time scale of this I am not for a second trying to kid my self that this will be an easy one day wonder.

Every one please keep checking rib.net on Sunday for info requests as the resin dry’s ahhhhh forecast is for a max temp of 10c on Sunday so we should have time to get it all lined up before the resin sets.

Seriously do you think it would make any odds to cut this as 3 sheets then bond them?

[Dirk Diggler]

Originally Posted by mdt

Sunday is earmarked as the day to build a 5.4 transom.

So the questions are.

1: will 3 sheets of 18mm marine ply bonded be enough?

That's an unusually thick transom for a little boat, 2 x 18 mm is the norm. any thicker and you may run into problems with steering clearance/motor fit.

Originally Posted by mdt

2: how big should one make the knees?

I'd make them to midway between the top/bottom fixings of the motor.

Originally Posted by mdt

3: any one got any other words of wisdom?

Put each piece in seperate, on a couple of layers (or one heavy) of wetted CSM, them clamp/through bolt till it's gone off, them put the knees in and overlaminate everything. If you start in the morning, you'll be finished by tea time.

[r mcdonald]

You could release wax a smooth flat surface, gelcoat it let it set, add some layers of CSM,add a layer of plywood , add a layer of CSM , add the next layer of ply wood, then some more CSM , then a layer of bubble wrap, then stick a layer of plasic over the whole lot,and use wide plastic sticky tape to seal it. Apply vacuum to it to clamp it all together.
Make sure you wet out the plywood before you lay it on the CSM or you will get a dry joint.

To locate the plywood you could use some wooden dowels (so they don't slide around ).

You will end up with a smooth gelcoat surface .from the smooth table

If you use epoxy resin you will have to use it every where, as polyester resin dosen't
stick to epoxy resin. Epoxy sticks to polyester well.

The picture is the trasom I built for the RIB I am building.
Hope this helps.
regards
RPM

[Dirk Diggler]

That'd look excellent, but a smooth gel coat inner transom isn't the best surface to laminate knees to.

[r mcdonald]

Originally Posted by Dirk Diggler

That'd look excellent, but a smooth gel coat inner transom isn't the best surface to laminate knees to.

The smooth gel coat surface goes on the outside of the boat. If you use peelply between last layer of CSM and the bubble wrap that will give you a good surface for bonding you knees to. Any resin supplier can supply peelply. The bubble wrap spreads the vacuuum over the whole panel.
regards
RPM

[9D280]

Originally Posted by Dirk Diggler

That's an unusually thick transom for a little boat, 2 x 18 mm is the norm. any thicker and you may run into problems with steering clearance/motor fit

You reckon? That's 54mm Mine's about that thickness, and only rated for a 110Kg 60. (granted no bracing) Plenty of room for the clamps to fit - and my Aux won't go over the back of a 90Hp rated Ribcraft transom - I think it was a 5.8, so not too far off the size of a 5.4.......)

36mm transom wouldn't fill me with much confidence to hold a 90 up!

[Dirk Diggler]

Originally Posted by r mcdonald

The smooth gel coat surface goes on the outside of the boat. If you use peelply between last layer of CSM and the bubble wrap that will give you a good surface for bonding you knees to. Any resin supplier can supply peelply. The bubble wrap spreads the vacuuum over the whole panel.
regards
RPM

I wasn't aware that he was removing the whole transom, I assumed he was leaving the main lay up, and just replacing the Wood and overlaminates.

As for vacuuming, I expect that's a bit too technical for an Avon, and not that easy to source the materials and equipment!

[Dirk Diggler]

Originally Posted by 9D280

36mm transom wouldn't fill me with much confidence to hold a 90 up!

I'm not suggesting that the transom should be a total of 36mm, just the wood that's in it. Assuming the outer laminates are being used (see above post) then a couple of csm's to bed the first 18mm ply on, then a couple more csm's, followed by another 18mm ply, then overlaminated with more csm's, woven and csm, (or combi), then the knee's, and more over laminating will result in a transom well in excess of 50mm, which is the recognised std for a transom!!!

FWIW, a sterndrive transom cannot be more than 50mm, or you can't fit the transom assembly.

[mdt]

Originally Posted by r mcdonald

You could release wax a smooth flat surface, gelcoat it let it set, add some layers of CSM,add a layer of plywood , add a layer of CSM , add the next layer of ply wood, then some more CSM , then a layer of bubble wrap, then stick a layer of plasic over the whole lot,and use wide plastic sticky tape to seal it. Apply vacuum to it to clamp it all together.
Make sure you wet out the plywood before you lay it on the CSM or you will get a dry joint.

To locate the plywood you could use some wooden dowels (so they don't slide around ).

You will end up with a smooth gelcoat surface .from the smooth table

If you use epoxy resin you will have to use it every where, as polyester resin dosen't
stick to epoxy resin. Epoxy sticks to polyester well.

The picture is the trasom I built for the RIB I am building.
Hope this helps.
regards
RPM

Well that is a very fine job you are doing on that transom, shame I don’t have a vacuum pump… no I would get shot if I was to have the dyson in the garage. I have still got the outer layer of glassfibre as I really felt it would be handy to have some thing to use as a starting point. So once I have the ply wood bonded together I was looking to bond it to what is left of the transom and then build in the knees and stringers etc.

[jwalker]

Follow Dirk's advice. 2 x 18mm plus all the laminating. Make sure the old surfaces you are laminating to are rough and clean and have a big area. There will be no chemical bonding to your old hull surface so your resin has got to grab hold to anything it can for adhesion.
Take the knees right down to the hull and also laminate the deck to them.

Your transom will be angled so, if you want a good fit, the new transom edges (particularly the bottom edge) will need to be angled to fit against the hull and each 18mm piece will need to be offset so the angled edges align. If the top is to be the usual right angle, then the18mm transom ply panels will not be the same size.

Good luck.

[mdt]

Originally Posted by jwalker

Follow Dirk's advice. 2 x 18mm plus all the laminating. Make sure the old surfaces you are laminating to are rough and clean and have a big area. There will be no chemical bonding to your old hull surface so your resin has got to grab hold to anything it can for adhesion.
Take the knees right down to the hull and also laminate the deck to them.

The idea behind not just the knees but the stringers too was to do all we can to increase the amount of the old hull we could glass too. And to try and triangulate the whole lot.... Grinder at the ready to rough up the hull

Originally Posted by jwalker

Your transom will be angled so, if you want a good fit, the new transom edges (particularly the bottom edge) will need to be angled to fit against the hull and each 18mm piece will need to be offset so the angled edges align. If the top is to be the usual right angle, then the18mm transom ply panels will not be the same size.

Aye, I had worked out that there was to be a need to cut each section slightly differently to get the required steps to fit the hull floor as other wise the angle of the transom would create quite a gap once the full 36 or 54mm width had been stuck in place.

Originally Posted by jwalker

Good luck.

should this not be may the rib gods smile on you? Thanks

[r mcdonald]

Sorry I thought you were removing the entire transom.
Unless you can sand the transom perfectly flat.You could mix some filler with resin when bonding the first layer of plywood to the existing transom laminate,that should fill up any voids between the two. If you use straight resin it will just drain out the bottom of the join.
regards
RPM

[Downhilldai]

Originally Posted by jwalker

Follow Dirk's advice.