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Author Topic: Mysterious cracks on hull  (Read 314 times)

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Geoffreykwright

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Mysterious cracks on hull
« on: May 20, 2021, 05:09:35 AM »

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.
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Sundowner III
Catalina 34 Mk II Hull 1494 (Built 2000)
Toronto, CANADA

scgunner

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Re: Mysterious cracks on hull
« Reply #1 on: May 20, 2021, 06:17:29 AM »

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.
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Kevin Quistberg                                                 Top Gun 1987 Mk 1 Hull #273

glennd3

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Re: Mysterious cracks on hull
« Reply #2 on: May 20, 2021, 10:26:08 AM »

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.
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Glenn Davis
Knot Yet
1990 Catalina 34 Mk 1.5
Hull 1053
TR/WK
M25XP
Patapsco River
Chesapeake Bay Maryland

Ron Hill

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Re: Mysterious cracks on hull
« Reply #3 on: May 20, 2021, 02:11:42 PM »

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
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Ron, Apache #788

waughoo

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Re: Mysterious cracks on hull
« Reply #4 on: May 20, 2021, 08:42:10 PM »

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. 
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Alex - Seattle, WA
91 mk1.5 #1120
Std rig w/wing keel
Belafonte

Geoffreykwright

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Re: Mysterious cracks on hull
« Reply #5 on: May 21, 2021, 05:06:48 AM »

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
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Sundowner III
Catalina 34 Mk II Hull 1494 (Built 2000)
Toronto, CANADA

Ron Hill

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Re: Mysterious cracks on hull
« Reply #6 on: May 23, 2021, 01:58:34 PM »

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
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Ron, Apache #788

paule

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Re: Mysterious cracks on hull
« Reply #7 on: May 24, 2021, 08:21:56 AM »

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
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Paul & Lynn Erb
Yachta Yachta Yachta
C34 2003 #1634
Rotonda West, FL 33947

glennd3

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Re: Mysterious cracks on hull
« Reply #8 on: May 24, 2021, 11:27:14 AM »

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.
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Glenn Davis
Knot Yet
1990 Catalina 34 Mk 1.5
Hull 1053
TR/WK
M25XP
Patapsco River
Chesapeake Bay Maryland

Ron Hill

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Re: Mysterious cracks on hull
« Reply #9 on: May 24, 2021, 03:01:18 PM »

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
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Ron, Apache #788

Sailing Amok

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Re: Mysterious cracks on hull
« Reply #10 on: May 27, 2021, 01:39:18 PM »

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.
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Aaron & Kristina
1998 C34 MKII "Coral Wave" M35B
The Great Lakes
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