Stringer repair

bjf66

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Managed to pickup fuel tank in weekend made of 4mm aluminium with all stainless fittings, which holds 75 gallons (300 Litres),, which was approx. 88" long (2250mm), so that may need to be modified however its a good start

received trailer back from being sand blasted and put a coat of cold galv paint on that

need to chop out more of water ballast tank up front, however turned my attention to the transom as have been trying to figure out how to change the transom angle from 20 degrees which it is now to 10 degrees to suit a Arneson surface drive

So decided to have a closely look at transom and used router at a depth of 3/4" on outside to check the structure

To my surprise found rot, so had a further check and decided to bite the bullet and cut transom out from outside as I need to adjust the transom angle to suit drive

The ply was shot, had a hell of a lot of glass on outside

anyways few hours routing, cutting chipping, need to sand tomorrow

The top part of transom is solid timber no rot
will have to build up inside of transom as well as outside to get the 10 degree angle, however this will work out better than the wedge which I was original going to use

Now have worked out what is happening in transom angle and the need to rebuild transom can proceed to clean up inside of transom where stringers will attached as more cutting/grinding needs to be done here
 

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Baylinerchuck

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need to chop out more of water ballast tank up front, however turned my attention to the transom as have been trying to figure out how to change the transom angle from 20 degrees which it is now to 10 degrees to suit a Arneson surface drive

So decided to have a closely look at transom and used router at a depth of 3/4" on outside to check the structure

To my surprise found rot, so had a further check and decided to bite the bullet and cut transom out from outside as I need to adjust the transom angle to suit

Won't that buildup increase the thickness of the transom? Is there a max transom thickness when dealing with a surface drive like a mercruiser outdrive? Just curious, I really have no idea..... That is one unique looking rear end on that boat! Very cool.
 

bjf66

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Baylinerchuck,
there are just 4-5 x 1/2" dia bolts (depending on the drive size, mine is 4 bolts) that holds the drive in, with support plate on inside of transom to spread the load, so no limit on the thickness of transom........just determined by length of bolt

Today I plan on measuring up and see how the angles work out and what needs to be done to ensure get plenty of strength in lower section of the transom
at least now with cutting transom back to the fibreglass, all the holes will be plugged, and we know what we are dealing with
Just need to be sure we do the job correctly
 

bjf66

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chipped wood out of the transom so now nice and clean
made transom template, and cut from 18mm marine ply
may need to make transom in 2 parts
main transom looks to be close to 15 degrees, however need the lower keel/transom to be 10 degrees, so with the mock up its coming in close to 8 degrees which is good, then run the glass cloth over this to tie it all together
started making stringers, will sandwiched marine ply: 18mm/16oz/12mm/16oz/18mm which should get close to 50mm thick, then fibreglass stringer in and tab them in
 

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bjf66

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managed to get some VE glassing down yesterday evening, nice 27c in victoria
placed some 16oz cloth on existing transom to even out the bumps
then spread full 16oz cloth+VE over the existing transom which have clean canvas to work with now
glassed the new 18mm transom with 2x16oz cloth
need to cut another 18mm transom and glue the 2 pieces together was going to use VE+ cabosil to thicken the mix
things starting to happen so good boost in confidence
 

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ondarvr

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You keep mentioning "cloth" you don't want to use cloth with VE if you aren't using CSM too.
 
Last edited:

Woodonglass

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I Totally agree with this^^^^. Poly and VE resin MUST utilize CSM in the layup to achieve proper adherance to the substrate.
 

bjf66

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yes looks like I goofed up there, oh well grind it off and start again
went out and purchased 600 grm CSM today
managed to play around with transom yesterday, and get to approx. 5 degrees in lower part of transom where drive will bolt up, so thats fairly good
decided to go with laminating 3x18mm marine ply
will get the transom sorted first
 

bjf66

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ondavr
I have a question for you
when laying up the transom, once you have the CSM on and layed the first 16oz bias cloth, do you keep going with the additional layers of 16oz or woven roving, or do you have to lay CSM in between each additional layer of 16oz/or woven roving ?
It seems I received different opinions today when asking
 

JASinIL2006

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I'm not ondavr, but I'll take a crack at it...

I think you are supposed to alternate CSM and and the cloth. The reason for this is that the cloth has lots of strength, in part due to its long fibers, but it is has weaknesses in several directions, particularly if the load runs counter to the directions of the fibers. CSM, which isn't as strong because it's fibers are much shorter, actually complements the cloth because CSM's fibers run in all different directions. By creating laminates with both CSM and cloth, you get the best of both worlds. Also, the binders that hold CSM together break down in resin, causing the CSM to interconnect with layers on either side of it, essentially locking all the layers together into a strong laminate.

You may have heard that it's not necessary to use CSM if you're using some sort of biaxial cloth like 1708, which combines a layer of CSM with cloth into one material.
 

ondarvr

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Like what JAS said, you need to alternate the layers.

​The other part is the terms used to describe types of glass, some make sense and some don't. Cloth is one the terms that is used incorrectly quite often, some people call all types of glass, cloth, others use it to describe everything except CSM. Cloth is actually just like a very light weave of roving, and is almost worthless in boat building and repair when using VE or polyester, ironically it's most often referred to as boat cloth. Cloth is used a great deal with epoxy though.
 

bjf66

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Dear All, excuse the delay in responding, as was travelling in Japan last, and this week, and couldn't get access to the site to log in, surprisingly its working today

so far have laminated 3 x 18mm marine fly together with CSM 600grm (2 oz), and Peanut butter
placed another layer of 600grm CSM over new transom
placed layer of Double Bias 617 gsm E -glass fabric down

Then was going to place the new transom piece into boat and start laminating from outside
1. layer 600grm CSM
2. layer 617 grm double bias E-glass fabric
3 layer 600grm CSM
4. layer 937grm double bias fabric
not sure whether will need any additional layers of 600oz CSM and layer of 617grm double bias fabric of the 937grm double bias


then add a layer of 617 double bias E-glass fabric onto existing inner fibreglass transom (which was not removed from boat
layer of 937grm double bias fabric

Need maximum strength for 650hp through transom to surface drive
not sure whether this is over kill of not it should give me close to 3mm of glass???
 

bjf66

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Updates
1. managed to glue the laminated the lower part of new transom (3*18mm Marine ply/CSM/PB) into the original fibreglass vineer
2. added PB to raidus on inner transom
3. smoothed out the remaining outer transom, and made PB to smooth out the lower parts of transom to achieve even surface for bonding
4. glued in the first 18mm marine ply/CSM/17oz double bias, using VE/PB
5. bolted in with 4*10mm Threaded rods and 90x45mm pine, used electrical tape on threaded rods to ensure could get them out after the boned held

Next stage, laminating 2*18mm marine ply/CSM/PM for the lower part of transom, try and get this finished this week
 

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bjf66

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routered the top 60mm of lower laminated transom so the next 12mm marine ply will over lap the first joint by 50mm
presently the transom as shown in last picture is at 46mm (1.8") thick without CSM/PB joint
Will put another 12mm ply on top of this to build transom out to original and then start applying:
- 2 layers of each 2 oz CSM /17oz bi-axial
- 1 layer of each of 2 oz CSM and 24 oz bi-axial
- and if need be a further layer

Then turn attention to inside of transom
 

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bjf66

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well managed to glue the last 12mm ply onto transom, depth worked out well with outside of ply coming just below the original transom level
can start building up alternative layers the CSM and double bi-axial fabric on the outside transom
 

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bjf66

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spent weekend on boat tapped out at midnight on friday, achieved what I wanted to do
Cracked open 2nd 20kg pail of VE

On outsude of transom:
- fillet the gaps between original transom and new timber
- fillet and radiused the lower extended new transom into the original boat
- more grinding
- 1st layer of 600grm CSM on
- 1st layer of 17oz biaxial fabric on
- needs some grinding

On inside of transom
- PB the dips in transom,
- On filling in lower transom to ensure this section is flat for the support plate that will be bolted to Arneson drive to spread the load on hull
 

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bjf66

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Only had time last night to put skim coat of PB on inner transom, and 1st layer of 600 (2 oz) CSM
 

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