Stress Cracks

[Basscat7]

Lets separate the fact from fiction on stress cracks:

All boats have the potential for stress cracks, it is the nature of the beast when working with fiberglass. Some premier boat companies products will have very little stress cracking due to the more expensive vinyl ester resins and gel coats used in the laminating process.
Resins and Gel Coat are petroleum based products, virtually the same chemical makeup, the difference being Gel Coats have pigments or Polyflakes added to achieve the various colors/flaked hulls.Most manufacturers use standard Ortho blend Polyester resin, costs is around $ 25.00 a gallon retail. A couple manufacturers use high end Vinyl Ester resins that are more resistant to stress cracking, these run around $ 45.00 a gallon retail...........an 80 % price increase over standard marine resin.


Flexing is what causes the majority of stress cracks (obviously hitting a dock or object in the water will cause some ). The cracks usually occur in the resin base below the gelcoat.

Gel coat applied around an 18 mill thickness (approximately 1/16"  thick ) will flex a lot more than thicker gel coat making it less prone to cracking
Use of Vinyl Ester Gel Coats with the Vinyl Ester resins will help eliminate stress cracks even more.

Also the manufacturing technique will play a large part in whether a boat will have the potential to develop stress cracks.

All fiberglass hulls are made a couple of ways:

Gel coat is sprayed on a waxed mold over a layer of clear coat Gel, then backed up with various layers of resin saturated fiberglass cloth. a fine layer of glass goes in first to cover the gel coat and to prevent print thru of the heavier fiberglass cloth to the outer layer of gel coat.

Hand laminated : Glass mat is cut in patterns to fit the boat mold and is laid in the hull and wetted down with resin, then rolled with small finned rollers to remove all air trapped between the gel coat layer in the mold and the wetted glass mat, also to remove any excess resin.

Or : Sprayed with a chopper gun, which shoots resin and chopped up strands of fiberglass roping into the mold at the same time, then rolled the same way to remove air/excess resin.

An ideal glass to resin ratio is 40 % glass to 60 % resin for open molding, this ratio gives the best strength to flex ratio.

The way the top cap and hull are mated together is another piece of the stress crack puzzle, most companies are still putting the two pieces together the age old marine standard of bolting/screwing the top cap to the hull...this allows more flexing when running in rough water.

Newer marine construction methods involve glassing the top cap to the hull, forming a monocoque, one piece hull/cap/transom, further helping to eliminate flexing of the cap and hull at separate times.
Less flex = less stress cracks. 

There are a lot of variables involved in Fiberglass boat construction, but newer Resins/Gels/Construction methods are helping to eliminate stress cracking in the higher end boats..........but You will pay for this technology in the price of the boats.

Most stress cracks are cosmetic in nature, and if repaired will generally return in the same place due to the flex of the hull in that spot.
Rule of thumb is,  if you can insert your fingernail in the crack it is NOT cosmetic and should be repaired before the inner glass mat absorbs any water.

[Wishing2BFishing]

The words "stress cracks" freak me out a little.  When I read about things like that, I think "glad I got the aluminum" especially since I seem to always find the rocks.

[bfitch]

i should put a picture up of my boat where someone hit it. (who shall remain nameless, right JJ : :grin: ) anyway, how would you know if the glass mat absorbed any water? it rained pretty hard on my boat after it got hit, but it still floated the next day when i went fishing

[Basscat7]

Impact cracks are different than stress cracks, depending on the force of the impact.....fiberglass is very strong and able to absorb fairly hard impacts without cracking the glass mat/resin.........same rule of thumb applies though....if you can fit your fingernail in the crack, it should be fixed before using the boat.....any crack that wide has the potential to also have cracked the mat/resin base and allow the mat to absorb water.

Run your nail over the crack at a 90 degree angle, stress cracks will be felt, some may stop your nail...but if your nail does not " drop " into the crack then it is cosmetic and as long as you can deal with the looks  it will not harm the boat.

[fishinjim]

i should put a picture up of my boat where someone hit it. (who shall remain nameless, right JJ : :grin: )

lol.  i already let the cat out of the bag in last week's oneida thread.  go ahead and make fun of my lack of boating skills... i deserve it.

was thinking stan might be able to give the damaged area a peek at octorara, but it looks like you'll be missing that one, so i think a pic would be a good idea.

if its bad enough, i might see if my insurance will handle it. 

[bfitch]

if i remember, ill get my brothers camera tomorrow and take a picture.

[fishaddict1426]

let it go, it gives it character :grin: not every boat can look like a basscat

[Pillager]

basscat:  (n) boat that looks good but doesn't catch fish... or is that the guy in the basscat?   :grin:

[MicroZer]

          haha.,Maybe it is the basscat.,What is Basscat again? :grin:



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micro molding