Fibreglass Boat - Hair-Line Crack in Gel-Coat

[strobe1970]

Hi,

When cleaning the boat today I noticed a hairline crack in the gelcoat which wasn't there last week (last trip). Not sure what caused it -- the trip today was on totally flat water (Clyde River) and less than 10knots when we were underway. We didn't hit anything and the launch and recovery was uneventful. I've attached a photo - not very good but you can just see the crack.

What can cause this ? -- and should it be repaired before next trip ? Anybody know any good Fibreglass repairers in Batemans Bay ?

Regards,

Paul

[Crunchy]

Is it a scratch or definitely a crack? It's hard to tell from your pic but looks like a scratch....

[strobe1970]

Yeah the photos aren't the best. Its almost definitely a crack - I showed the missus and a mate when I found it and the consensus was it was a crack.

[johncar]

Well for a start you should consider the strap over the boat, not to say it's the direct cause but I have seen countless glass boats with gelcoat fractures around those straps and caused most often by being pulled down too hard. My thoughts are if you must use one of these, only tension it enough to take any slack out of the strap and no more, as it only needs to stop the boat bouncing off. Tying down from the transom is a much better method if at all possible and if not it is probably better to try and make it possible.
Also if you have to use a strap try and place it on or very near to a rear bulkhead and not in an unsupported area of side deck where the side can flex and be pulled in if you are a bit over zealous with the tensioner.

[cormorant]

What hull is that? What age ?

There are lots of fancy ways to check the thickness and integrity of a hull and confirm if they is a crack or.....

How have you determined it is a crack? Can you get either side to flex?

Check the roller under it isn't too high or one either side of it collapsed? Trailer isn't rusted through ? Wake at the pontoon whan launching?

[WalrusLike]

........Wake at the pontoon whan launching?

I didn't know about this...... What can you tell from the wake?

[myusernam]

might be cause by that tie down strap?

[chris69]

How about tie down strap makeing the boat flex on those rollers over all not the best set up with the combonation of the strap down force on small single point rollers.

[cormorant]

I didn't know about this...... What can you tell from the wake?


My thought was along the lines that some hulls are layed up very lightly on the sides as in normal use there are very few horizontal loads. Ie you need strength in keel and running surfaces and on the top coaming. If it is built lightly on the vertical sides then a smack against a sharp sided pontoon from another boats wake can cause that style of horizontal cracking ( if it is a crack). Sort of another reason not to ever raft up at a pontoon as it can become both the weight and moment of your boat and the other tied up boat versus a solid pontoon. Ya normally see it is smaller tenders that are lightly built


The other times I have seen this damage is where people tie boats off to pontoons at launch ramps and they tie them too tight and as the pontoon moves up and down on wake the ropes don't stretch enough and huge stress happens . Same with buffers at wharves on the sides of boats not spreading the load. The hard rubber "D" nosing on the sides of launching ramp pontoons effectively concentrates all the load 6 -12 inches above the waterline on a very small surface area with a curved boat hull that can be the whole weight of the boat on one point.

Not sure if the way I have written that makes sense. Get ya wife to tread on your hand - not to bad then do it with high heals - lot less surface area to a lot more point load - stress.

Solution - use your own buffers and leave a few inches slack in your mooring lines and don't let people raft up to you

[wirlybird]

im going with the strap i have done that damage before the exact same way

[fishfeeder]

A question about your Strap, Does it go over your hull at the back of the boat where the back seat is..??
If so, that area I would think should have enough Horizontal support.. Maybe a picture showing more of the area would help..

I have a strap that goes across the back of my boat, just like 99% of boats I have seen at the Boat ramps and I have never heard of there being any problems caused from it.. be good to find out if it could be an issue or just a myth ??

Cheers
Brett

[WalrusLike]

.......Get ya wife to tread on your hand - not to bad then do it with high heals - lot less surface area to a lot more point load - stress.
.....

holy crap... You must be joking... Have you seen my wife???? :)

I don't need to encourage her to step on me... She is happy to do that without provocation. :)

( only joking dear.....)

Yeah thanks for the explanation... I didnt understand the earlier post but I get it now. And a very good point it is too... I will be much more careful about side loads on the hull now.

[cormorant]

If nothing unusual has happened at the wharf the guys saying it is strapping down too tight are probably on the money and that may have happened if it wasn't tight up against the winch post and has moved while on the road wedging against the trailer under brakes.

Think for my own safety I'll stay away from wife comments - it'll only end in tears


Edit - just read your post below and recognise the boat now. Looks so good. It may have been their all along and with you pressure washing and polishing etc it was so clean it wasn't noticeable till now with a bit of brown water residue in it? If it is a crack it is possibly not from your recent ownership? Like someone else mentioned I like to see a double row of rollers under the area at the transom I strap and it might just be me but it looks quite a way to the rear of that trailer. Is there a set of rollers very near the transom? .

[strobe1970]

Thanks for the feedback so far.

I have attached another picture to place the first two in context - black line is the approximate location of the crack and red is the approximate location of the strap (not very good picture again - have to zoom in a bit to see the lines I've drawn). Its a Carribean Concorde (Hull 2001 - the outboard is a 2002). The trailor and boat are in good condition (I think). The strap does go forward of the rear seats and I don't remember the crack being there when I put the strap on prior to the trip back. I usually have the strap firm (but not what I though is over tightened - but what might be firm to me might be overtightened to others). I've haven't used anything other than the look/feel to me and others opinions to determine its a crack (thought it better check before trying to move or do anything else that might cause further issues).

To see the history of the boat (for me anyway) see this post :).
http://www.ausfish.com.au/vforum/showthread.php?184953-Advice-on-First-Boat-Caribbean-Concorde&highlight=concorde


Any recommendations for gelcoat/boat repair at Batemans Bay. The engine was serviced at Hunts Marine (and quite happy with the service provided there - they didn't mind me asking lots of questions and watching much of the process).

regards,

Paul

[Crunchy]

The reason why I asked if you were sure if was a crack is that I have a very similar looking line on the side of my boat, its a scratch (So I says to the wife, "What part of of tell me when I'm close to the fence didn't you understand"::)) but its just a scratch in the gel coat and not at all an issue other than asthetic, I guess if I hadn't known when I did it I might think it was a crack. Hopefully yours is the same buddy! Not sure how you can tell if its is a crack or not though......but you may be in a panic for no reason. Good luck with it.

[strobe1970]

Yeah I was hoping as well - I was trying to convince myself it was just a scratch and even tried to convince the missus and then my mate when I showed them I started with "Thats just a scratch isn't it" which was quickly followed by "Nup - reckon thats a crack" - grrr. Anyway - could still be wrong.

Paul

[Fish_Two]

Hi Paul,

You are getting flexing in the side walls, the crack is a movement crack in the gel coat from the flexing taking place,
Check around the bulkhead area above and below floor line, and check the other side, check your under floor areas

Either way its a crack, and fibreglass cracks from stress/movement/flex

Glen

[Jarrah Jack]

Could well be an insurance job. worthwhile checking with your insurance company before you do anything. Serious cracks need to be fixed from both sides.

[johncar]

Looking at your transom setup you would need to be light on with the strap tension regardless if it is the cause or not. I have seen gelcoat cracks right up the whole side radiating in smaller to larger diam circular patterns from the strap over point. It is just a good idea to only pull it down to take the slack out of it but no real tension. Think of it more like a seat belt.
The crack if it is a crack is probably just cosmetic and my bet is the strap still, but you would be wise to try in check out the internal structure around the floor for any soft spots or swelling just in case.

[strobe1970]

Thanks for all the advice much appreciated. Based on feedback I've decided to get it professionally checked to be sure. I'll report back what I find out. I think I'll be moving the strap further back where there is more strength near the transom and be more judicious around how tight I do the strap.


regards,

Paul

[strobe1970]

The verdict is in. It was a crack in the gel coat only. Probably due to the strap being a little tight. Not an expensive repair job (thankfully). No other cracks or indication of fatigue in the hull. Very happy chappy.

Paul

[Si]

Get ya wife to tread on your hand - not to bad then do it with high heals - lot less surface area to a lot more point load - stress.

ummm, ok...........

[WalrusLike]

Thanks for the update. It's good when the OP comes back with the results.

Glad it's all good, happy boating!

[Crunchy]

Good outcome, I've learn't something too, I dont ratchet the crap out of the strap any longer!

[WalrusLike]

Yeah I should've said that also..... I don't over tighten it any more either. Good info guys, thanks.

[johncar]

Excellent news :)