Hull deflection from trailer boards

Apr 6, 2014
1
604
I noticed yesterday when preparing to launch for the season that the board supporting the keel had failed over the winter. So, more of the weight of the boat was bearing on the side boards of my trailer. These boards are 2x6x10ft. At the aft end of one of the boards, the load was sufficiently concentrated to cause a noticeable deflection in the hull.
I know the Capri hull is 1 inch solid fiberglass, and I did not see any cracks in the outer gelcoat, or inside the starboard locker. I will have the boat in the water next week, but I wanted to ask for opinions of whether the hull is likely to be damaged.
Since I don't exactly know the type of fiberglass used, the flexural stiffness of the hull is maybe half that of aluminum, so maybe when the boat is lifted off the trailer, the deflected part will return to its normal contour. I'm worried that I may have damaged the hull.
Seems like the most likely failure mode would be cracking of the interior surface in tension? Or, maybe flexural shear cracking inside the material?
Any opinions would be appreciated. Thanks.
 
May 23, 2007
1,306
Catalina Capri 22 Albany, Oregon
Not sure the hull is an inch thick; deck and transom, maybe.

If the indentation isn't too deep, and wasn't there too long, then I bet it will come out while the boat is in the water. Worst case, you maybe put some paving blocks in the locker for a week or so to help, but I bet you won't need to. Do get those boards replaced though, because the keel skid is supposed to carry the weight, not the stands.
 
Jan 22, 2008
496
Catalina 310 278 Lyndeborough NH
The Capri hull can be as little as 3/8" thick where the bunks might be pressing against it. Other areas are thicker.

Check the bilge area to see if there is any separation of the fiberglass to the cockpit support.

The bunks should be "form-fitting". They should bend and "caress" the hull surface. The rigid 2" x 6" x 10' boards do not flex when placed on end. The result is the hull rests on the boards at a single point. All the weight of the boat not supported by the keel is transferred to those two points (port and starboard). The hull WILL push in trying to spread the load.

I use four adjustable Brownell boat stand tops set in 2" pipe that is bolted onto the crossbeams of my trailer. The front set is located near the mast support bulkhead. This area does not flex. The rear set has no inner bulkhead for support. It DOES flex.

To reduct the deflection, I place a 1" x 6" x 10' board (decking material) on the pair of boat stand tops allowing the weight of the boat to make the board flex, supporting the weight over a total of 10 square feet versus the four points of the boat stand tops.

This way, the hull NEVER deflects.
 

shnool

.
Aug 10, 2012
556
WD Schock Wavelength 24 Wallenpaupack
Yep, check for stress cracks if there are none the boat will survive... you'd be amazed how tough fiberglass is. If you follow the goings on over at TSBB, someone just had a garage roof collapse on their boat... bent stanchions, pulpit, stern rail, and noodled the mast... fiberglass was fine... go figure!

Fix the bunks... repair the keel support (which by the way I've had mine walk off my trailer while I took it for a day sail, replaced it with 2x4s for the day... then fashioned a more practical keel support after the boat was permanently in the water (funny part was I had to get the boat off the trailer because the 2x4s I used were from the A-frame I built to raise the mast!).

Again, pretty tough boats.