What to do about cracking hull where rub rail is fastened.

L

louxwe

New member
I have only had my boat for about a year and haven't used it too much. When I pulled it out in Sept to trailer it for surgery I noticed there is a crack in the hull along where the rub rail was riveted to the side of the hull. The crack appears to be on the front portion of the hull, looks to be on both sides but worse on one side. When researching the boat I kind of remember this being an issue.

What is the standard accepted way to fix this, or did I just buy a lemon? From the interior you can start to see chips in the fiberglass and light coming through and on the outside under the rub rail you can see about a 1/4 to 1/2 inch crack at the widest under the rub rail. Looks like the rivets just caused a stress along that line.

Not sure what to do now, is there some advice pictures on how to repair this? Should it be a big concern? Costly to repair? Images in my folder... can't seem to figure out how to attach images here?

http://www.c-brats.com/modules.php?set_ ... _album.php
 
I looked at your photos, it doesn't look too serious, thick gellcoat can be very brittle and easily chips. Don't worry, I think many cbrats with specific knowledge of the problem will chime in and help you.
 
The hull to deck joint is under the "rub rail". It is glassed on the inside--not the outside. The aluminum extrusion and plastic insert covers the joint.

I do see the cracking, inside and outside--not bad--and I would not say a "lemon. You may want to pull the rub rail; doing this you will remove the rivets. You can put more glass on the inside--and a layer of epoxy and tape glass on the outside, under the rub rail, for a permanent "fix",

Are there any places where it looks as if the boat has been hit--with radial cracks out from an impact area? Any areas of delimitation of the V berth or the anchor locker--aft bulkhead?
 
I thought one of the things about the C-Dory is that the joint between the hull and the deck was bonded in the mold meaning that there was not really a join there anymore (i.e. the hull and deck are bonded to be one piece).

There is some mention somewhere that this process of joining the hull and the deck is a discriminator from other boats.
 
The hull is one molding, the deck/splash well/sides of the cabin another molding. The "deck" molding is set on top (not a typical "shoe box" where the deck fits over the hull flange. Then several layers of glass are bonded on the inside of the hull to deck joint. So is this any more of a one piece than a shoe box which is joined with a adhesive sealant or a "Glue" like "plexus"?

I think it is better than holding the hull to deck joint with extrusions and sealants or pop rivets.

Increased cure time in the mold makes a boat more likely to be "True" to its molded lines. I had heard at one time, that the deck was put on the hull when it was still in the mold--but I don't know if that is being done currently...
 
I don't see any cracks extending down or something that looks like it was hit or ran into something, I am just concerned that the crack will extend along the rub rail and eventually the front top of the deck will be loose. I found in this video some mention that certain years of C-Dorys had some issue with deck cracking from the rivet joints going through and that C-Dory did something later to fix them. Would thickened epoxy be enough to repair it? Would you have to go back in somehow and sand inside the crack to get the thickened epoxy to stick? I'm worried about putting something that is rigid or hard into the crack and causing it to get worse with vibration.

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Thanks, Bill[/url][urlhttps://www.youtube.com/watch?v=wCIjkHzEEgU[/url]
 
Some of us don't think it is that super serious, but if you want a bullet proof structural fix, use a small grinder with a coarse sanding disk and remove the gellcoat along the inside of the seam. Using epoxy resin put on 4", 3" and 2" wide layers of fiberglass cloth tape, then gellcoat. Your deck will absolutely not come off. This is an easy job but will create a dusty mess.
I'm still not convinced that from what I can see of your problem that it is seriously structural, but that it is more local in nature. It just seems unlikely, as these boats are generally well built, that such a simple element of the building process would have a major failure.
This is just my opinion from on far, for true peace of mind why not have a local pro look at it and give you an opinion?
 
You can put thickened epoxy over the cracks if it makes you more comfortable. I cannot tell you exactly what type of fiberglass material (mat or cloth) was put over the hull to deck joint. Typically it was probably mat. For the 38' boat we built we did exactly what Micah described--but the glass cloth was alternated with Matt, 18 oz roving, then mat and cloth for a finish. The hull was still a bit "green" then--and no contamination, so we used polyester resin. In our case we were under no time constraint, so left the boat in the mold, for several weeks, while we put the deck on (as the same way the C Dory does).

As Micah suggests, epoxy is the item to use, if you wish to. If I was going to do that, I would just do where you see the cracking, not the entire boat. Your boat is 13 years old, and nothing has fallen apart yet...very unlikely to. II am not aware of any of the hull to deck joints failing because of this issue in C Dorys. If you are down Pensacola Way, bring your boat to my house, and we will take a look at it--sound it out etc...
 
The rivets loosen over time water gets in then freezes and pops out the in side gelcoat, no big deal. Replace some of the rivets with stainless machine screws fender washer and lock nuts. Just in the area that is lose and not every rivet. Then clean off the any caulk out side and recaulk the top of the rub rail only with marine silicon. I carpeted the side walls in v berth to cover the nuts and the cracked gelcoat three years and no problem.
 
As B.A. said, thickened epoxy does the trick - at the end of the crack (both ends if applicable) find the very tip of it and drill a small hole (stop drill it) with a #30 drill bit. This will turn linear stress into circular and stop the crack from growing (if you catch the very tip of it). Having been a fan of old airplanes and old boats I've don a lot of this kind of thing - you can use wax paper to get the hull shape exact by pressing the epoxy with that and removing the paper later. Good luck.
 
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