yesterday, I was coming back to shore after a fine sailing session and I had a bit of upwind sailing to do before getting to shore.



As always, it is not the greatest aim for a boardless catamaran but it was moving fairly fine until I noticeds that my main was sheeted block to block. I seem to remember that I was never able to sheet block to block because of my moderate mast rake so I was wondering:



Is it possible that my hulls are getting softer and giving in to the center in front of the front beam?



My boat is a very old (1984) Nacra 5.7 with the fiberglass hulls (no core). Some spider cracks are there in many places on the boat but I never noticed before that the hulls were soft.



Are there any tests or checks that I could do to see if the hulls are getting soft?



Is it possible to repair and strenghten them?



Could I swapp the hulls (port to starboard), I would only have to change the aluminium trampoline rail and the jib rail.



I was planning to perform some work on the hulls this winter like removing the decks and applying some fiberglass on them. Also I should do a keel job and a rudder job.



Next time I drive down to my lake, I will bring a flashlight and inspect the interior structure of the hull to try to detect anything wrong with them.



I am welcome to any suggestion



Please be especially nice if you plan to tell me that my hulls are dead because I really cannot afford any bad news about my cat.

Charles,

You could measure the distance between your rudder pintels or alternatively the port gunwale on the port hull and port gunwale on the starboard hull just to get the distance between the hulls centreline.

Measure between the bow tips then rig the boat and measure between the bow tips. Sheet the mainsail on as tight as you can and measure between the bows again. You will get some tow in, the question is how much.

Just as an indication when I do this to my wood Taipan I get a(15mm) just over half an inch diff. Sheeted on as hard as I can.



I've heard a Hobie 18 can flex as much as two inches but have not measured that myself.



My personal opinion is if you get more than two inches you couldn't call your hulls stiff and may want to explore your options.



Hope this helps.

Phill

1984 is not very old. Old, yes, but lets not bury the thing in the cemetary, yet. Consider perhaps that your sails are getting tired, too. Are they 1984 vintage as well? Age brings sag (sorry ladies). It would seem that you aim not to sail a beat to often. Did you sheet in especially hard to get back to shore out of necessity, surpassing your normal amount of effort? Did you change your rig and create more rake (or maybe soneone else did)?



As far as your hulls go, rap on them with your knuckles. just kock on the hulls all over and listen for really wild changes in the sound. If you are knocking along the hulls from stem to stern and you hear a nice solid response and then in some particular spot you get a uninspired thunk, you may have some fiberglass problems. Before jumping to any terrible conclusions, do this to both hulls and listen for symmetry in the sounds from left hull to right. Don't confuse bulkeads or stringers with bad spots (do 5.7s have bulkheads or stringers?)



Just my $0.02 worth

With your boat on dry land, put your mainsail up. Measure the distance between your bows. Now crank the mainsheet. Measure the distance between your bows again. There will be some difference, but it should be minor, maybe about an inch max. A big difference indicates things are getting weak.



Other possibility - your headstay or bridle is coming apart, maybe underneath the plastic coating.



If it's the stays - replace 'em!



If it's the hulls, well... You'll have to figure out if they are mostly safe, just starting to flex. If so, maybe a bridle foil like 5.5, 5.8, and 6.0 (or something like the H-17 sport pole) would be worth a try. It would help keep the headstay forces from pulling the hulls together like the normal bridle wire setup does.

uh, maybe your main is stretching, and you're sheeting harder, and the air was medium, and it went block to block.



again, maybe the main is stretching, is it the Dacron main?

You mention the symptom is you can sheet block to block, and never were able to do that before. This does not mean hulls are shot. There are others causes that can create this effect. Are you sure you set up the mast with the forestay position the same place on the bridle as always? If you didn't, your mast would be "raked" farther aft, and you would experience the same symptoms. Also, check the forestay and bridle wires theoretically, the nicropress fittings could start slipping prior to catastrophic failure. I would check items like these before you get depressed about your hulls.



Now about the NACRA hulls - pre-foam, with internal stringers. They can get soft eventually, and there was a real good thread a few months back about how to detect it, and how to fix it. Search for "soft spot" and "hull delamination", also on the Hobie forum.

I'm sure others will chime in with more direct links.

Charles,



If your Nacra hulls are starting to fail in such a manner it is usually because the stringer on the inside / side of the hulls has separated from the hull. However, if this is the case, the hull will be obviously "oil canning" (collapsing like and old metal oil can) just forward of the front beam. I think it more likely that the sail is stretching or that something else might be happening.

Also check your dolphin striker. The bolt holes on either end corrode and move sideways. Under load a little beam sag can allow a surprising amount of "mast rake". Maybe the mast ball is stripped out too (Sunlight can really tear them up and make them chew away suddenly) I think chronic hull deflection would be evident under load. Beam deflection is less visible from the wire. It also leads to beam cracks at the hull saddle, so check you have a bind on the striker. "unscrew" the post under the ball to tension. Don't know a setting (well actuallY I do - you TENSION IT SO THAT WHEN YOU SLAP IT JUST SO IT KIND OF MAKES LIKE THIS - YEA.) Somebody help.

Thank you all for the advice and the support



I should go back to the boat in a few days.



I will check the standing rigging but since I always perform a visual inspection of the wires before I go out in strongs winds, I am positive that it is still OK.



I will also open the hatch of the boat and inspect the forward hull from the inside. With a miror and a flashlight. I will be looking at the strigners and posts



Finally, I will perform Phil's test of calculating the hull deflection under load after checking the Dolphin striker nut.



Anyways, I will still try to repair the hulls (keels and decks) so I might put a little glass inside



Again, I will keep you all posted hoping that the boat isn't quite ready to retire