Bow weakness?

[marshwatcher]

Any info available on delamination in bow area?

My husband, crew on an Alden Challenger headed from Maine to Ireland, reports - "We were beating into confused seas off the Grand Banks (5/06) when several waves destroyed (literally) the cross hull supports at the V of the forward bunks. One was original; several were replacements when we had put in a new (and slightly smaller than the original) holding tank. A number of the hollow ribs cracked. The hull then had 1/2 - 1 1/2 inches of play.

We returned to Mt. Desert Island, there was a little crazing but a 2" core showed no delamination. The yard is putting in two new bulkheads, rebuilding the ribs, extra fiberglass, etc.

Has anyone had a similar experience? Advice or suggestions?

Is this a good boat for a trans-Atlantic trip (last Q from a worried wife)? Prompt reply would be appreciated as they are planning to leave again very soon.

Thanks!

 

[Quetzalsailor]

Bow weakness in old boats

Our LeComte North East 38 has similar construction and the same failure. The vee berth beams frame into a stringer glued to the hull, using a couple brass(bronze?) screws at each end. Basically, they're 'toenailed'. A decking of 1/4" plywood lies loose on the beams. Several of our beams have pulled out and I found the decking bounced into dissarray.

Your Challengers have hat channel stiffeners, like frames, but they're not very big compared to the hull layup. (Compare them to the 'ribs' under the decks in a concrete parking garage built with 'double tees': it's an apt comparison.) They are far better than nothing but not nearly enough for the flatter areas of the bows or under the cockpit. The LeComte has a 'bilge stringer' from end to end and some big hat channels aft which serve to stiffen that long overhang. The bilge stringer is about 5/8" deep and 6-8" wide. Alden and Tripp were trying to solve the same problem by similar means.

It's down the list, since we're just putzing around the Chesapeake, but I intend stiffening the bows. I think my approach will be to add guts to the beam support stringer and to gusset the beams to the support. I don't think I'll add bulkheads or frames since they'd have to extend up past the berth and would affect the appearance of the ceiling. A far better repair would be to remove impediments and add, say, a 1/2" foam core and an interior layup to the flat areas. An important consideration is to not locally overload the hull with stiff spots. Powerboats often 'float' their bottoms on intersecting frames and stringers to avoid the bottom layup coming internally delaminated.

Both Challengers and North East 38s have been sailed around the world. I'd say they're a bit light for the job, but with caution, care and attention to appropriate sailing routes and seasons... Serious ocean cruisers do not have the huge cabin windows we do and they're much more heavily built.

Additionally, we have 35-40-45 year old boats; while polyester is apparently a pretty stable chemistry, osmosis and fatigue surely take their toll on the original stiffness and strength. The flexure that broke the deck beams will occur at ever lower loadings unless it is restrained.

 

[marshwatcher]

Thank you for this very informative reply!!