Boat modification – insurance question

[moresparks]

I am in the process of replacing failed old twin engine sterndrives with a brand new modern single engine sterndrive in a budget cruiser and the overall HP will be similar.

Before anyone comments … I have already gone past the point of no return!

The modification work to the transom is considerable, but to make the project viable cost wise, I was hoping to undertake most of the work myself.

It means completely removing the inner ply “core” and replacing with a new Marine Ply Core. The new core will be 2 times 18mm ply shaped and bonded together. Finally tabbing and fairing the old twin sterndrive shield holes and cutting a new centre hole for the new shield.

The old core has now been removed and the outer skin all left intact and the surrounding area made good and reinforced where necessary. As the old hull was built with polyester resin, all new work will be undertaken with Lloyds approved polyester resin to be compatible.

The next stage will be to “bond” the new transom core to the outer skin (from the inside) with thickened resin, then the transom core will be “tabbed” from inside using and layers built up to the required thickness as specified by the engine manufacturer.

Now my question…

So far I have undertaken all the non technical (heavy labour) work myself, but do I HAVE to employ a specialist fibreglass technician to bond the new transom core into place for insurance purposes?

I am waiting for a response from my insurers.

I am no stranger to fibreglass work having been in the past on fibreglass courses and undertaken various projects such as fitting a new diesel inboard including bearers to a boat and fitting a sail-drive in another.

The reason for asking is timescales in trying to get a technician to schedule in the work as I have already waited several months, also costs as I am on a tight budget and the weather / temperatures are on the rise.

The finished work will be surveyed in accordance with the Insurance.

I am hoping to get answers from some who have done this type of work in the past.

Thank you…

 

[Andrew_Trayfoot]

Can't see any reason why you can't do the work yourself.
Take lots of photographs and keep a record of what material you use.
Possibly engage a surveyor...

In a side note, I understand that you where you are trying to bond to old polyester it was better to use epoxy.... Others may have a view on this...

 

[moresparks]

Re. Using Epoxy… I did consider this but my understanding from the builders of the original boat and independent advice was that there is a remote possibility of bond failure with epoxy bonding to the original layup and that the gel-coat finish will not adhere very well to the epoxy. The laminating together of the two sheets of marine ply will be in epoxy for strength.

 

[ash2020]

I used to be a laminator in a former life, a long time ago. My understanding then was that polyester will not bond to fully cured polyester, on a molecular level. That's the reason for using epoxy. I think it needs a bit more research but good luck with the project.

 

[William_H]

Yes plus one for using epoxy. Polyester Flow coat should be ok on epoxy. Once epoxy is hard. Obviously not as good bond as flow coat on polyester stil;l "green" ol'will

 

[Boathook]

I was told and read that epoxy sticks to polyester better than polyester. Also epoxy has about twice the strength of polyester for the same lay up.

 

[Poignard]

If you haven't already seen it, you might find this WEST manual helpful:

https://www.westsystem.com/app/uploads/2022/10/Fiberglass-Manual-2015.pdf

And I have found the WEST agent in the UK very helpful:

The European Home of PRO-SET, WEST SYSTEM and Entropy Resins.

Support - Wessex Resins & Adhesives

 

[Graham376]

I used to be a laminator in a former life, a long time ago. My understanding then was that polyester will not bond to fully cured polyester, on a molecular level. That's the reason for using epoxy. I think it needs a bit more research but good luck with the project.

I've heard that as well but then the opposite from a surveyor who used to be yard manager for Dickies of Bangor. Many years ago, I needed to beef up the keel stubs on our Berwick and because I would be advertising it for sale shortly afterwards, got the surveyor to write the repair specification and inspect it at stages and issue final report, didn't cost much for his services. He was very specific about using polyester, not epoxy.

 

[moresparks]

Many thanks for all your excellent advice - I will give this very serious thought.

My first choice would have been epoxy, but I was advised by the surveyor not to, as he knew the boat layup very well and he advised polyester.

As I need to be 100% in the structural integrity and to satisfy the surveyor who will pass this on to the insurers, I have to bow to his advice. Also the final external finish will be gel-coat "matched".

I am also looking into using vinyl-ester resin for the transom bonding and exterior finish, as a good compromise if I cannot get the fiberglass technician in reasonable time.

I will undertake more research.

Thank you again for your advice.

 

[Graham376]

By coincidence I've just been downloading and reading our insurance schedule and they state in terms and conditions - Statement of Fact, Assumptions - The vessel has not been modified, examples include but are not limited to changes to the cabin or hull, changes to the rig or additions such as a stove, generator, mains power or include a different engine than supplied, extending the superstructure, a different rig or sails.

I wonder how many of us have not bothered to advise insurers of changes such as engine?

 

[William_H]

Many thanks for all your excellent advice - I will give this very serious thought.

My first choice would have been epoxy, but I was advised by the surveyor not to, as he knew the boat layup very well and he advised polyester.

As I need to be 100% in the structural integrity and to satisfy the surveyor who will pass this on to the insurers, I have to bow to his advice. Also the final external finish will be gel-coat "matched".

I am also looking into using vinyl-ester resin for the transom bonding and exterior finish, as a good compromise if I cannot get the fiberglass technician in reasonable time.

I will undertake more research.

Thank you again for your advice.

Vinyl ester is lovely stuff to work with. Sticks well to old polyester similar to epoxy but easier to get to harden where you can add more hardener to get faster cure. ol'will

 

[Keith 66]

You sound like you know what you are doing. Why get a fibreglass technician in? Is there actually such a trade? Any of us who have been in the trade for long enough can call ourselves that. So can a lot of monkeys.
If you are bonding a plywood core against an original grp transom your main problem will be avoiding voids. Usually i would use a polyester bonding paste for such a job. Freefix is one but is quite stiff so easy to get air voids. Crestafix is better over big areas as its quite creamy.
You can also get a Vinylester bonding paste. As said above Vinylester resin is good stuff for repair work & for years has been my go to resin for good repairs. It uses the same MEKP catalyst as polyester but has adhesive & strength properties approaching epoxy but without any compatibility issues.
Personally i would not use epoxy on a polyester hull repair because of compatibility. Good preparation is the key to a good repair not using epoxy because its perceived to be better. Crap prep & an epoxy repair is likely to fail just as soon.
Many times i have seen people doing a repair with steep short bevels, crappy blunt discs resulting in polished surfaces, Contamination from antifoul, bilge oil etc. No resin copes with contamination epoxy worse than most.
I would also ask East coast fibreglass for their recomendation.

 

[Refueler]

To get Polyester surface ready to be bonded to - I recc'd :

Oven Foam Cleaner to remove all traces of foreign material / dirt etc.
Well rinsed away.
Acetone brushed over surface to soften the surface and let vapourise off

Surface should then be good to bond to.

As to Insurance ... as an Ex Yacht Surveyor - (not enough boats over here to do it seriously anymore) ... I would advise as another says - plenty of photos showing progression of work. You can compile into a paged report.
Find a friendly Surveyor who can verify your work and provide report to go with your photographic record - to pass to Insurers.

Of course as you already have done - Inform Insurance Broker of the work and intended Surveyor etc.

If all set out in logical and sensible manner - there should be no reason for Insurers to be a problem.... as long as they are informed properly.