Transom replacement project

[Sea-Dog]

I have a 4.5M Sea Sprite half cab of early Eighties vintage (I suspect).

It has previously had a partial transom replacement from the rear skin, so I decided to go in that way too, as it looked really crappy.


The previous repairer had coated the entire exterior of the "repaired" transom with some sort of beige coloured bog. In some places, it was up to 6mm thick.


It was hard and inflexible. It was bonded well to the existing gelcoat and repaired fibreglass areas. It looked absolutely crappy, so I had no hesitation in removing the bog and original gelcoat to see what I was left with.



A large area in the middle of the transom had been cut out and replaced with more ply. The new ply was in worse condition than most of the original ply.


The transom is quite strange, in that it is stepped. The ply was approx 25mm thick at the top, extending at that thickness down for about 240mm (Level with the outer chines). It then stepped down in thickness to only 12mm thick down to the bottom of the hull.



That seems AWFULLY thin to me......



It HAD a 115 Hp sitting atop it until recently. All of the ply was wet. One area of ply in the top starboard wing of the transom closely resembled dry leaves. I stuck my finger into it, and all that was left of the ply were a few dry, paper-thin layers.



I reckon I should go with the same thickness of ply from top to bottom.



The hull was originally rated to 85Hp. I'd like to be able to stick 90Hp on the back. (and still keep the insurance company happy)




What thickness of ply should I use? 50mm plus glass, or would 35mm plus glass be sufficient?

[Sea-Dog]

Floor is solid glass - no ply.

It is a single mould that is in the shape of an inverted hat. It serves the function of stringers as well.

There doesn't appear to any timber below floor as far as I can see under the floor from the rear of the boat.

I may have to drill an inspection hole under one of the bunks to make sure.

[blaze]

IMO
3 x 12 mm laminated together, dont use bog use a product called Qcell, dont step, use the same thickness all the way down. Where the drain plug goes through- remove all ply for about 50mm around the hole and replace with qcell (one of the places moisture ingresses into transom)
cheers
blaze
ps
wear face mask and eye protection, baby power on the body prior to commencing work helps relieve itching

[Sea-Dog]

Thanks Blaze, 3x 12mm it is then.......


That means that I will have to cut back a bit of the floor I suppose? or...........

Is it necessary to glass the bottom of the transom to the bottom of the hull, or is it enough to glass it to the floor, sides and splashwell? (Considering the full fibreglass construction of the floor/centrewell assembly)

( I will have to remove the rear of the splashwell to accommodate the thicker transom )

A grinding we will go, a grinding we will go.............

I already have disposable overalls, long gumbies, long rubber gloves, goggles, and dual canister respirator.

I just don't know how long to keep the disposable overalls..... they come up alright after a wash (Yeah, I know - bl00dy cheapskate)

[ashh]

if you do get itchy, have the hottest shower you can take, doing this opens up the pores in your skin. Dont 'scrub' at your skin, but brush in the same way your hairs grow to brush and rinse away the fibres, otherwise youll snap the fibres off in your skin and youll be itchy for ages.
I use to work in airconditioning factory lining the insides of AC duct with insulation, even with wearing protective gear, it finds its way in. Have fun

[finga]

What a job
I'm glad it's you matey and not me. I hate the itchy's.

Another little hint....overalls over the gumby's. That way the dust cannot settle in the top and work it's way down into the socks.

[finga]

A question for all Eddy the experts...
Why don't they use solid glass for transoms???
Looks like this boat has a solid glass floor.
Is it a weight thing or a flex thing or what??

[BM]

Solid glass would mean no elasticity whatsoever so under the load of the engine thrusting the transom would crack.

The pics of the rear floor area look like glass over ply to me. There has to be some type of stringer arrangement otherwise the hull bottom would be flopping about the place with no support.

Cheers

EDIT: just had a closer look at the floor pics. Yes, definitely all glass. Unusual arrangement. Wouldn't be original I wouldn't think, may have been done at the time the transom was repaired. May have been a home done job.

[Sea-Dog]

The floor/stringer setup has to be factory made. It looks like its all a single mould.

The lines are too straight and even to be a home job.

I don't know what its like in the front half of the hull though.

I hope its the same deal all the way through.

I will drill a couple of inspection holes at some stage soon and see what goes on at the front of the boat, under the floor.

I know of one other bloke that owns a seasprite hull. I will email him and ask some questions.

[Sea-Dog]

Gone a bit further now. I needed extra space to work and fit the extra thickness of transom. So instead of cutting through the top deck, and removing the splashwell and rear seat section, I thought I'd go a bit more radical and remove the entire top deck.

It will give me heaps of access to all the areas I need to. At the moment, the top deck has been separated from the hull, but is still sitting in place.

I plan on removing the entire thing and placing it on drums out of the way, so I can work unobstructed.

[johnnytheone]

G'day SeaDog,
It's actually not as gruesome as you first think. There are heaps of good sites on the net that give good details on how to go about it. (www.rotdoctor.com is just one). I took out a stern drive and filled the hole up - easy! A whole transom is obviously a bigger proposition. Just have a couple of beers and think about it first. One thing that's worth considering is using a compound that gets into the matrix of any timber and waterproofs, and up to a point, reconstitutes it. Epicraft "Everdure" is one such product. It's a bit exy but it goes a long way. It's also good for bung holes and wherever you've got a raw hole through a timber bulkhead etc.
Try to find a bulk supplier of resin and matt etc, as its vastly cheaper. One other thing - for Christ's sake don't get catalyst in you eyes!!

[ozscott]

...is that right about the transom. My seafarer has only wood in the middle of the transom where the engine sits (unlike the old Haines I had where the wood spanned the entire width of the transom - from gun'l to gun'l). It has a little bit of soft in it, but no flex whatsoever when you hang off the end of the motor and apply bodyweight to it at full tilt. I spoke to Lindsay Fry about it (Seafarer owner) and Nelson Rabel who assessed the boat before purchase and both said that the sheer amount of glass used on the transom and because the transom is convex means that the wood could be completely gone and it wouldnt matter at all to the integrity of the transom and boat - having said that my outboard is about half the power of the maximum permitted according to the plate. The thickness of the straight fibreglass on the old girl is amazing - for example when I cut a hole in the foredeck/prow for the anchor rode, the deck is over an inch thick of pure fibreglass. The bloody dash is 3/4s of an inch thick at all points of solid glass....so I dont really know why the wood is there. Its a point that i have wondered about before Finga.

When I had my V163 half cab (70's Haines) the transom was very sound, but the floor got rot in it and when I cut it out the stringers were completely rotten also - just thin glass shells. What dissapointed me was that the original floor was only 5mils or so thick and with only about 2mm of glass on it....AND NO glass at all on the underside of the ply, so that any condensation would tend to eat away at the floor from the inside. I had Holloways down the coast put in new stringers and also a 12mm ply floor that was glassed heavily on BOTH sides...the guy who bought it off me 6 months or so later has got a boat for life!

Cheers

[BM]

... I spoke to Lindsay Fry about it (Seafarer owner) and Nelson Rabel who assessed the boat before purchase and both said that the sheer amount of glass used on the transom and because the transom is convex means that the wood could be completely gone and it wouldnt matter at all to the integrity of the transom and boat

Fair enough I suppose. But then, from a production cost analysis perspective, if the timber isn't required, then why the extra cost and labour to put it there in the first instance???

Methinks the provided response is tantamount too "oh, oh...."

Cheers

[ozscott]

I know what your saying matey, but there is no shame in a boat that has rot that is 30 years old - the condensation is enough and you cant keep that out. Also Nelson Rabel is a well respected marine surveyor, and had nothing to gain by telling me the same things as Lindsay Fry....and the proof is in the pudding in terms of the rough sea performance with not even fine crows feet anywhere on the aft end of the boat, and no flex at all..having said that my transom is not soft to touch and its only in a couple of small areas where if you drill you get some softer wood. I also filled mine with Evidure when I got it to stablise the spores that would be in the soft wood.

Cheers

[Sea-Dog]

It's a bit early to be asking this at the current stage, but at least I won't forget if I ask now.

I was saying the bloke down at Bias about how I'd like to glass the inside of engine mount holes after drilling to lessen the chance of water ingress.

He suggested something a bit different.

Mark out the position of the holes, then drill quite oversize holes.

Fill the holes with resin/qcell putty then after that has fully set, just drill the correct size holes for the engine mounts through the resin putty.

Then just use oversize washers (& sealant) both sides of the transom and much lesser chance of water getting in.

To me it sounds like quite a good idea.

Opinions?