Lagoon440 rebuild

[IslandStyle1]

Hi -I’ve been around the forum for a while but never posted anything. I am technical but not highly experienced in the field of GRP. I would like some info or confirmation please -I recently purchased a lagoon 440 which was an insurance “write off”. Both Hulls are damaged “holed” and I have stripped the guts out of the hulls for repair. Yip that was a big job and everything eventhe engine rooms are clear ..
The question is:- do Lagoon use Vinylester on all their Catamarans on manufacture?
I have been told that it is best to use expoxy resin for the “Bonding”layups -but I have also been told that if the same type of resin is used as the original boat build then the bonding to the existing boat will be successful I.e Vinylester
The intention is to make the Hull as good or better than original and to incorporate sacrificial keels rather than fixed keels with what I think are clever sumps incorporated.
Thanks for any input which will be welcome!

[44'cruisingcat]

I'd use epoxy. It does secondary bonding best.

[motion30]

First choice for the strongest repair would be epoxy, second choice would be vinyl Ester the last choice would be polyester. It doesn't really matter what the hall is originally made from, unless it was originally epoxy which I doubt

[rabbi]

Originally Posted by IslandStyle1

Hi -I’ve been around the forum for a while but never posted anything. I am technical but not highly experienced in the field of GRP. I would like some info or confirmation please -I recently purchased a lagoon 440 which was an insurance “write off”. Both Hulls are damaged “holed” and I have stripped the guts out of the hulls for repair. Yip that was a big job and everything eventhe engine rooms are clear ..
The question is:- do Lagoon use Vinylester on all their Catamarans on manufacture?
I have been told that it is best to use expoxy resin for the “Bonding”layups -but I have also been told that if the same type of resin is used as the original boat build then the bonding to the existing boat will be successful I.e Vinylester
The intention is to make the Hull as good or better than original and to incorporate sacrificial keels rather than fixed keels with what I think are clever sumps incorporated.
Thanks for any input which will be welcome!

According to what I read so far Lagoon uses Vinylester only on the outer skin (gelcoat) to reduce risk of osmosis. The fibreglass layup itself is polyester as its cheaper.

I have very little experience with doing my own fibreglass work but secondary bonds will be stronger using epoxy. Epoxy is much stronger in most regards.
But this comes at a price: cost is higher, some folks develop allergic reactions to epoxy, and epoxy combined with polyester can be complicated work on (the different properties make e.g. sanding of epoxy patches in a polyester hull tricky).


You should definately seek professional help. I mean professional, not just someone local who has successfully done a few patches. The large resin importers / dealers know their stuff, and can advise you on material and professional contractors to use.
If you are determined to do it yourself, get some professional to train you for the first few days until you get the feel for it.

If you are too cheap even for a few days of professional training you will just mess it up. In that case you can also just haul the hull to the dump side and invest your budget in beer & cheap women.

[IslandStyle1]

Thank for that input ....I will be using a professional to do the actual work for sure once I am sure of the correct procedure .and I have a reasonable budget -but I’ve spoken to a number of experienced people and even their strategies differ somewhat .My understanding now -and I will understand more before I embark on the actual repair is as follows .Expoxy resin while been 20% stronger has very good bonding characteristics-which in this repair would be very important -to both Vinyl Ester and Polyester finishers -but Polyester and Vinyl Ester do not Bond well to Expoxy.This is important because one strategy was to do two layups of Expoxy and then finish with either of the others -but that seems would be an incorrect strategy .
Clearly Expoxy is more expensive-but the intention is to do this repair once -properly and hopefully never to have delamination issues.also it seems Expoxy and Gel coat ( which is polyester ??? Are not good together -please correct me if I’m undstsnding incorrectly
Thank you for your input again and I will use all the info I get to hopefully get the best end result -and not end up in the junk yard ...

[Thumbs Up]

You need to search back through these forums. This has been argued about a lot here. Pay attention to posts by Minaret. I haven't seen him on here lately. A lot of people here will say that you have to use epoxy but no one has ever seen a properly prepped polyester to polyester secondary bond fail. If you do it in polyester you have the option of a gelcoat finish. With polyester, the resins will cost you half as much and the repair will take half the time. No need to use epoxy to repair a polyester boat!

[rabbi]

As said I am no expert. I just tried a few things and some worked, and others not so much.

If my understanding of the Lagoon layup is correct you are not going to bond anything against vinylester. Only the first very thin layer of gelcoat is vinylester, so only a fraction of a millimeter. All structural (the area with fibres) is pure polyester.

If the poly doesn't stick to epoxy is true is not quite clear to me.
Check out the youtube channel "boatworks today". Yet another source of information.
This guy did a long series of boat repair and gelcoat videos, and even some testing of gelcoat over epoxy (which he did together with the company producing the "West System").
Bottom line was: With good preparation no problem to do poly gelcoat over epoxy.


Good luck with the rebuild!

Originally Posted by IslandStyle1

Thank for that input ....I will be using a professional to do the actual work for sure once I am sure of the correct procedure .and I have a reasonable budget -but I’ve spoken to a number of experienced people and even their strategies differ somewhat .My understanding now -and I will understand more before I embark on the actual repair is as follows .Expoxy resin while been 20% stronger has very good bonding characteristics-which in this repair would be very important -to both Vinyl Ester and Polyester finishers -but Polyester and Vinyl Ester do not Bond well to Expoxy.This is important because one strategy was to do two layups of Expoxy and then finish with either of the others -but that seems would be an incorrect strategy .
Clearly Expoxy is more expensive-but the intention is to do this repair once -properly and hopefully never to have delamination issues.also it seems Expoxy and Gel coat ( which is polyester ??? Are not good together -please correct me if I’m undstsnding incorrectly
Thank you for your input again and I will use all the info I get to hopefully get the best end result -and not end up in the junk yard ...

[rabbi]

Originally Posted by Thumbs Up

A lot of people here will say that you have to use epoxy but no one has ever seen a properly prepped polyester to polyester secondary bond fail.

"Properly prepped" may be the key.

I had a failed secondary bond in my Lagoon 380 when I bought her. A large panel (holding the AP actuator) that was laminated to the inside of the hull had separated.
No clue if the factory did a proper prepping job. Maybe not.

[44'cruisingcat]

Originally Posted by Thumbs Up

A lot of people here will say that you have to use epoxy but no one has ever seen a properly prepped polyester to polyester secondary bond fail.

I've seen several polyester to polyester bonds fail. Of course the excuse will be that they weren't "properly prepped". But how would you know?

[smj]

Originally Posted by IslandStyle1

Hi -I’ve been around the forum for a while but never posted anything. I am technical but not highly experienced in the field of GRP. I would like some info or confirmation please -I recently purchased a lagoon 440 which was an insurance “write off”. Both Hulls are damaged “holed” and I have stripped the guts out of the hulls for repair. Yip that was a big job and everything eventhe engine rooms are clear ..

The question is:- do Lagoon use Vinylester on all their Catamarans on manufacture?

I have been told that it is best to use expoxy resin for the “Bonding”layups -but I have also been told that if the same type of resin is used as the original boat build then the bonding to the existing boat will be successful I.e Vinylester

The intention is to make the Hull as good or better than original and to incorporate sacrificial keels rather than fixed keels with what I think are clever sumps incorporated.

Thanks for any input which will be welcome!

If your intention is to make the hull as good or better than original then use epoxy for the repairs.

[neilpride]

Originally Posted by Thumbs Up

You need to search back through these forums. This has been argued about a lot here. Pay attention to posts by Minaret. I haven't seen him on here lately. A lot of people here will say that you have to use epoxy but no one has ever seen a properly prepped polyester to polyester secondary bond fail. If you do it in polyester you have the option of a gelcoat finish. With polyester, the resins will cost you half as much and the repair will take half the time. No need to use epoxy to repair a polyester boat!

Thank you, yes , argued to the extreme, most boats here in sxm are fixed with polyester and gelcoat after hurricane IRMA , holes, rudders, decks , cabin roofs etc.. the trick is the skills involved not the resin , epoxy is stronger but you must avoid create hard spots in a thin poly panel , i stick in repairs to the OEM materials used in the construction, also using epoxy to patch large holes involve a full paint job , add to the budget if the boat have gelcoat in the construction ,epoxy can do the trick in many aplications and poly can do the job even cheaper in most cases..

[smj]

Originally Posted by neilpride

Thank you, yes , argued to the extreme, most boats here in sxm are fixed with polyester and gelcoat after hurricane IRMA , holes, rudders, decks , cabin roofs etc.. the trick is the skills involved not the resin , epoxy is stronger but you must avoid create hard spots in a thin poly panel , i stick in repairs to the OEM materials used in the construction, also using epoxy to patch large holes involve a full paint job , add to the budget if the boat have gelcoat in the construction ,epoxy can do the trick in many aplications and poly can do the job even cheaper in most cases..

A few months ago we had an above and below waterline repair done to our lightweight vinylester/ divinycell cored catamaran. I requested the repair to be done in the same materials as the build. It turns out they did a solid vinylester/ CSM repair, an absolutely disgusting thing to do to a performance multi. I contacted the original designer/engineer of the boat as well as 2 of the most respected multihull designer builders. All 3 said it was improperly repaired but was structurally fine, just way overweight. So how can a 3/4” solid CSM repair done on a lightweight catamaran build be fine, yet a couple of layers of cheap cloth saturated in epoxy over a balsa core on an overweight catamaran be considered unsatisfactory and produce a possible hard spot?

[neilpride]

3/4" in my book is nothing to consider with any resin used , its a seacock hole, but in the other hand the original poster mentions a write off L440 and i suspect the damage is by far more than 3/4" in diameter , diferent resins diferent properties... plug a 3/4" solid patch in a cored hull and make no diference , make a 4x4 foot patch in epoxy in a thin poly hull and its a diferent thing, the wonderful thing is to achieve the same with the same properties that had before...

[smj]

Originally Posted by neilpride

3/4" in my book is nothing to consider with any resin used , its a seacock hole, but in the other hand the original poster mentions a write off L440 and i suspect the damage is by far more than 3/4" in diameter , diferent resins diferent properties... plug a 3/4" solid patch in a cored hull and make no diference , make a 4x4 foot patch in epoxy in a thin poly hull and its a diferent thing, the wonderful thing is to achieve the same with the same properties that had before...

When I said 3/4” that was thickness not diameter or area. Various areas but one was probably 2’x5’.

[neilpride]

Well, cut a 2x5 cored panel and get another solid CSM 2x5 panel, they have the same tensile ,shear, compresion properties?