Mysterious cracks on hull

[Geoffreykwright]

Hi - hoping someone has some insight.  Another Cat 34 at my club has some mysterious vertical cracks on her hull on both port and starboard at the aft end just forward of the transom (both cracks very narrow and 3 inches in length).  I don't know their hull number - mine is 1494 from year 2000.  Their boat is 2002, but don't know the hull number.  What concerns me is that the cracks are almost symmetrical - i took three photos from behind and used blue masking tape to indicate where the cracking is.  You can see the the cracks are roughly the same length and same position.  (Again - the cracks are on the sides of the hull - the blue tape on the transom just shows positioning).  I could easily fill the cracks and repair the gelcoat - but I am concerned that since the cracking is symmetrical it might be indicative or a structural problem.  I don't have the history of the boat, so not sure if there was any grounding or collision, but cannot see any evidence of that.  I looked inside both lazerettes and could not see visible problems on the inside.  Could an improperly tuned rig crack the gelcoat?

Thanks in advance.

[scgunner]

Geoffrey,

It could be a lot of things, I'm not an expert, but based on the location it doesn't look structural. Could be due to natural flexing and expansion and contraction of a 20 year old hull. I'd think if anything bad was going to happen, it would have happened by now. I'd just do the repair and keep an eye on it.

[glennd3]

I have the same cracks on my 1.5 cat 34. I am marking them and watching if they get larger. I will probably have the yard fix next winter season.

[Ron Hill]

Geo : Have you confirmed that they are cracks that go all the way thru the fiberglass?  Or are they cracks in just the gelcoat???

A few thoughts

[waughoo]

Geo : Have you confirmed that they are cracks that go all the way thru the fiberglass?  Or are they cracks in just the gelcoat???

A few thoughts

They definitely look like gelcoat cracks to my eyes. 

[Geoffreykwright]

All - thanks for the feedback - these are definitely gelcoat cracks - I've not opened them up to see if the extend to the underlying glass (not my boat).  Inside the lazarettes looks fine - so I am guessing they are more cosmetic in nature.

As always - thanks for all of your feedback.

Geoff Wright
Sundowner III
Hull 1494

[Ron Hill]

Goe : To fill those cracks on your MKII and chips in the same place on the MKI boats - I used a filler and made a gelcoat paste which is MUCH easier to work with and fills nicely!  Then sand it with 1500 grit and you'll never notice it!!

A thought

[paule]

They look like stress cracks in the gelcoat. I just repaired mine last year by grinding them out filled them in but still have to gelcoat them, but the boat went in the water before I could gelcoat because of covid19

[glennd3]

Goe : To fill those cracks on your MKII and chips in the same place on the MKI boats - I used a filler and made a gelcoat paste which is MUCH easier to work with and fills nicely!  Then sand it with 1500 grit and you'll never notice it!!

A thought

I wish there was a way to practice this.

[Ron Hill]

Glenn : With a gelcoat paste it's easy.  I believe they call the filler for paste "micro balloons" ??

Put it on and the use a piece of tight wax paper taped over the fill.  Then - when dry lightly sand with rough 200 wet dry wet paper. Then final finish with 1500 wet/dry wet paper!!

A few thoughts

[Sailing Amok]

Our '98 has one in the same place. We gave the MagicEzy HAIRLINE FIX a go this year, and sadly, I wouldn't bother with it. There are no shortcuts in life. Next fall or spring we'll do it the right way as suggested by Ron.