Crack in hull below shaft

[YOYA]

Hello everyone!
Got cracks on both sides of the hull, 30 cm long on starboard, 40 on port, and they let water in slowly.

I have scraped my weterly conway to gel coat, let it dry for 7 months, did a lot of work, recoated it and was lowered back to the water yesterday. immediately I noticed a small amount of water coming in. stayed in the water for 24 hours and managed to isolate the source to a small area below the shaft just fw of the stuffing box. took the boat out again and the cracks were visible on the new antifouling, exactly where the crane strap was. these cracks were not there before. I know every inch of this hull. yes, the boat was on the starps for a whole weekend and that, plus the weaknesses of the hull in that area are probably the cause of these cracks.

the area did look and sounded weak , with light showing through, and is blistered with small 2-3 mm wide and 2-3 mm deep, non-acidic blisters in the gel coat. its a small bilge (40cm deep by 60 long by 30 wide cm) holding the stuffing box drip water and was always full of water before I got the boat and until I got to this yard and dried the bilges completely and renewed the packing in the stuffing box. however the boat was very dry after 7 month.

since access from the inside is very limited without removing the shaft (which I cannot remove),
Would a fix on the outside alone by sufficient to restore strength to this area?
It seems this area is not under a lot of tress when sailing, but the boat will have to be hanged on the crane straps again and I want to do whatever is possible so the strap wont crack it again.

how would you fix these craks?

your comments are highly appreciated!

(could not find a way to add images here using a tablet)

 

[Tranona]

Sounds like you need the services of a surveyor. Cracks of the sort you describe are not normal.

 

[Bobc]

That sounds structural. Insurance job.

 

[neilf39]

Looking at the shape of the hull behind the keel then with a lifting strop a lot of weight will be concentrated into a small area either side of the prop shaft. Over the decades of lifting it looks like there has been flexing here resulting in the failure you are now seeing. If water is coming in through these cracks it is pretty serious and sounds like it needs proper remedial work to strengthen it. As already suggested get a surveyor to check it out before it fails completely on a lift out.

 

[YOYA]

Thank you
Indeed the elders of the shipyard said they never saw anything like it. I have now with grinder enlarged the cracks, exposed the darker areas which eventually went through to the inside. Now I have a new through hull of about 14 cm long by 2-3 cm height...
Grinded to the laminate the whole area around, from the aft side of above the keel, to the propeller, a height of about 25 cm up to where the hull begins to curve out and discovered no other areas of delamination.
Yes neilf39, most of the boat's weight was resting on a narrow and compromised area just below the Stern tube. This is not a high stress part of the bottom and may not have been very thick in the first place. Luckily it did not cave in altogether when on the strap because it would have broken the shift and sunk the boat. It just cracked and let in a minute amount of water.
Now after I lay several layers of mat and resin, hopefully it would be stronger than any part of the boat. But to be lowered back to the water, it will be done with a strap on the keel, not on the newly rebuilt area.

 

[lpdsn]

I find it hard to believe that cracks like that have occurred simply as a result of the boat being badly lifted or supported. Fibre glass is not that weak. Something else will have occurred.

 

[Aja]

It's good boat management that when a boat is sitting in the slings, even when going for a tea break, that the boat is properly supported by sitting on it's keel on a block of wood or similar. I would employ a surveyor.

Regards
Donald

 

[YOYA]

We needed to remove the supports and put it on straps so we can do the paint final work.
That small and narrow bilge was weakened by decades of water sitting in it from a leaky stuffing box. The strap was pressing some 6-7 tons on a 7 cm by 30 cm wide area of that bilge from the outside for 3 days.
I don't see how a survey would help here.
After widening the cracks and finding two glass layers, the top one separated from the bottom one, it was easy to remove the bad parts with my fingers. Once the weak glass was removed, I'm left with a 14 cm long by 4-2 cm wide hole at the bottom of that bilge. The sides are about 2 cm thick. The remaining glass at the bottom is 2-4 cm thick.
I'm looking for input regarding the fix options
1) Lay resin and fiber in several layers from the outside, then same from the inside, as much as access permits via the gap between the shaft and the hull in that bilge

2) Create a mold made of resin and fiber, in the shape of the outside of the hull, then resin and fiber the hull from the outside and press the mold against it with supports. Let it dry then lay resin and fiber inside against the dry mold

3) lay resin and fiber in several layers from the outside only

4) reinforce the bottom of the bilge from the inside with hardwood tabbed to the sides of the bilge and resined, then add layers from the outside

Not sure if:
To use polyester or epoxy, or combine both, one outside the other inside.
Do the outside only.
Start laying inside or outside ( in case both in and out will get layers)
Reinforce with wood, SS, or none

Any input is highly appreciated

Thank you

 

[Fr J Hackett]

It's normal for lifting strops to be in the immediate area of a bulkhead to avoid compression, it is the owner that specifies the lifting points which are usually marked by stickers.

 

[Tranona]

Any input is highly appreciated

Thank you

The fact that you are asking for advice on so many options is an indication that you really need a surveyor with experience of these boats and of GRP repairs. The failure you are describing is not uncommon in boats of that era - I have seen a smaller Westerly about the same age that eventually required a new bottom to the hull because of failure of the poor lamination. It was just as you described - small defects when opened up got larger and larger as the laminate crumbled away. That skeg cum shaft log on your boat is a structural part of the hull, holding the two sides together.

If it were my boat, I would want a full survey of the whole hull and particularly the keel attachment and bilge reinforcement before slapping on extra laminations to what could be an unsound base.

 

[neilf39]

Beware that as there has been water getting through the gel coat then water could well have penetrated into the fibreglass further than is apparent so the weakened area may extend beyond what you can see. Also if you start using epoxy and polyester then epoxy is good to use over polyester but it is not recommended to put polyester over epoxy.
I would get someone with expertise to examine it and make recommendations. You can then decide if you want to try and do whatever work is needed yourself or get an expert in. Also have a word with your insurance company as they may have something to say. If at a later date you sink and the surveyor says it was the result of an incorrect repair then the insurance may be invalidated.

 

[Bobc]

The OP is clearly NOT going to get a surveyor or insurer involved. It sounds to me like the is determined to try to fix it himself, so there's no point keep suggesting that he gets professional advice.

1./ Grind out all the damp and get it 100% dry before starting any remedial work.
2./ With regard to what resin to use, I would just use polyester resin. It's what the boat was built with and Epoxy will just be a waste of money, as it adds no more strength on its own.
3./ Woven rovings have more inherant strength than chopstrand, so use that inside and out (300g or 450g +/-45).
4./ It sounds like you had some cavities in the original lay-up. Get rid of all the holes and gaps (fill the holes with Isopon P40).
5./ Use more layers than you think you need to (to get stength back into the hull, you'll probably want about 10 layers of 300g mat on the outside, and half a dozen layers on the inside too).

Hope that helps.

 

[earlybird]

This seems to be a substantial job in prospect. To re-build the laminate, I think that good access from the inside is essential for cleaning, grinding and re-laminating. Working from mainly the outside will make it more difficult to produce a sound, neat repair.
The shaft needs to come out IMO.

 

[Spirit (of Glenans)]

You need a surveyor to specify an effective repair scheme and a boatyard to execute a repair like this. It's not a DIY matter and in the event of failure; (a) you have someone to blame, (b) you still have insurance to cover.

 

[duncan99210]

Whatever the ins and outs of the repair, if the OP has any insurance beyond third party cover, then he would be well advised to seek a professional opinion on how to make the repair and who the insurers would be prepared to accept as being suitable to carry it out. If he doesn't take that step, then it is likely that the insurers will not pay out in the event of a future mishap. On the other hand, if he only has third party insurance, there's no need to consult anyone, just go ahead and carry out the repair to the best of his ability.

 

[richardabeattie]

Odd to see so many people replying without having read through the thread. The OP does not need any more posts telling him to get a surveyor. He does not want to. But rather him than me - it does sound fairly serious!

 

[lpdsn]

Odd to see so many people replying without having read through the thread. The OP does not need any more posts telling him to get a surveyor. He does not want to. But rather him than me - it does sound fairly serious!

I agree with a lot of that, but it is fair for others to post so that the OP at least understands where he stands compared to the majority of posters. And anyway, it's the internet so trying to control the answers is doomed!

My opinion whether he likes it or not is that if he doesn't have the expertise, and the confidence in it, to just go ahead with this without seeking help and support from the forum he needs to employ a good surveyor. Bit like that old story about the wannabe composer and Mozart.

 

[YOYA]

Thank you for the replies.
There is no and will not be any insurance but third party liability
So far I got half a dozen people, some professionals, some experienced boaters, to suggest how the fix should be done. This and the tips I got on other forums made it clear that:
Polyester and not epoxy
Alternating 450 & 500 grams of mat and roving (respectively), 2 of each in each layer. 4 layers all together, each with the above distribution. These are the layers that will go on top of the whole grinder area, extending from aft of the keel to the propeller which is an area of about 160cm by 70 cm. Yet first I will fill in the cavity itself with the above mentioned materials, until the hole is flush with the surrounding hull. It's about three cm at the bottom and one on the side. From the inside I'll place a removable piece of hard foam with weights on it to create support against the pressure of laying up layers into the hole from below.
The area is dry as bone. No flaking or delamination of material left there. The yard here is 30c and 40% humidity. The boat was in the water for 24 hours and had very little water in that bilge as I have constantly dried it.
Yes it is a big and complicated job but I believe it can be done properly and will result in an extremely sound area of the hull, an area that is not under stress while sailing, only when holding some 7 tons on a narrow point for 3 days. The boat will never be lifted again with straps on that area, only on the keel which is cast iron, yet in that aft area of the keel there is only one last bolt while fw of it its all double bolts.

As I have not done a repair of this size before, actionable comments are very welcome.

 

[pvb]

As I have not done a repair of this size before, actionable comments are very welcome.

OK, the story so far... your boat has had decades of sitting with water in the bilge area under the propshaft. Finally, you sorted the leak. Then you found blisters in the GRP, and then you found cracks right through the GRP. And now, despite the fact that there may be water ingress into the structure of the boat, you're planning to pop a bit of resin and glass over the affected area and go off sailing. And you apparently refuse point blank to ask a surveyor for advice, but are quite happy to accept advice from random strangers on the internet, most of whom will never have experienced the problems you currently have.

I've owned a number of Westerly yachts - Centaur, Pentland, Corsair - and I can't say that lifting any of them with a strop under the shaft area would ever have concerned me, for 3 hours, 3 days or 3 weeks. It should be rock-solid strong. Yours apparently isn't. Whether that's a result of decades of bilge water, or whether it was just another bad day when the Westerly men slopped resin in the mould of your boat 40 years ago, we'll never know.

You say that you'll only ever have the boat lifted in future with strops on the keel - this isn't general practice, and isn't a great idea. Lifting with strops around the hull is more stable and kinder to the boat.

Maybe it's the cost of a surveyor which makes you reluctant to hire one. If you ever want to sell your boat, a buyer's surveyor will no doubt pick up your repair and, if you don't have some evidence that the repair was done to a surveyor's recommendations, your buyer may well walk away. But, at the end of the day, it's your boat and your decision. If you render it unsaleable, you only have yourself to blame.

 

[Tranona]

OK, the story so far... your boat has had decades of sitting with water in the bilge area under the propshaft. Finally, you sorted the leak. Then you found blisters in the GRP, and then you found cracks right through the GRP. And now, despite the fact that there may be water ingress into the structure of the boat, you're planning to pop a bit of resin and glass over the affected area and go off sailing. And you apparently refuse point blank to ask a surveyor for advice, but are quite happy to accept advice from random strangers on the internet, most of whom will never have experienced the problems you currently have.

I've owned a number of Westerly yachts - Centaur, Pentland, Corsair - and I can't say that lifting any of them with a strop under the shaft area would ever have concerned me, for 3 hours, 3 days or 3 weeks. It should be rock-solid strong. Yours apparently isn't. Whether that's a result of decades of bilge water, or whether it was just another bad day when the Westerly men slopped resin in the mould of your boat 40 years ago, we'll never know.

You say that you'll only ever have the boat lifted in future with strops on the keel - this isn't general practice, and isn't a great idea. Lifting with strops around the hull is more stable and kinder to the boat.

Maybe it's the cost of a surveyor which makes you reluctant to hire one. If you ever want to sell your boat, a buyer's surveyor will no doubt pick up your repair and, if you don't have some evidence that the repair was done to a surveyor's recommendations, your buyer may well walk away. But, at the end of the day, it's your boat and your decision. If you render it unsaleable, you only have yourself to blame.

=1

Lifting under the keel is a bad idea and doubt any experienced crane operator would do it. Almost certainly it will not be balanced and could slip forward in the slings. It is meant to be lifted where you have been doing it and if the GRP cracks there is something seriously wrong and not sure just loading GRP locally to cover the cracks is sufficient to restore the structural integrity.