It looks like I have to install an inspection port in my H21. I have two already, 1 in between the two cross bars and 1 just after of the rear cross bar.

I have to do some internal repair work to were the wings (seats) go into the hull up forward. The only way to access this area is by putting an inspection port forward of the forward cross bar.
I cannot access this area with the middle access port because the centerboard is forward of that area.


Is there an issue with having 3 inspection ports on one hull? I don't think there is, they are very big beefy hulls, but figured I would ask.

My thoughts are if the fiberglass is still in good shape, adding another port should not be a problem. I wouldn't put it right at the crossbar, maybe a little ways infront to stay away from any extra forces associated with the crossbar.

A port behind the rear crossbar should not impact the strength of the hull in front of the front cross bar, maybe if you were putting the holes near each other.

--
Scott,
‘92 H18 w/SX wings
‘95 Hobie Funseeker 12 (Holder 12)
‘96/‘01/‘14 Hobie Waves
--

the area just forward of the front beam is heavily loaded by all sorts of invisible twisting and buckling forces

you very, very rarely see factory ports in that area, presumably for that reason...

but if you have to do it, you have to do it, the h21 isn't an ultra light racing machine and hobies have a reputation for being over built so hopefully you'll be ok

probably a good idea to cut as far from the beam as you can practically work and use as small a port as possible

Performance Catamarans( nacra ) told me that if I put a port in front of the front beam to draw a circle around the hull where the port was installed. That's where the hull would break.

skarr1

Performance Catamarans( nacra ) told me that if I put a port in front of the front beam to draw a circle around the hull where the port was installed. That's where the hull would break.

So we can try it on your boat to see what would happen???

Unless you have a cross beam that connects the bows and the for stay connects to it, as you sheet the main the the bows are pulled together. Nacra added the bridle foil to lessen the force. On all boat as you sheet the main you are puling up on the bows. There were photos of a 5.2 "airborne" that had the bow break off. Damon might be able to find the photos, I could not. I don't know if he had ports if front of the beam. I decided not to add any ports. Performance said I could add one between the dagger board and the front beam.

airbourne's 5.2 appears to have snapped it's bow off due to the internal stiffening stringers de-laminating from the hull, there weren't any ports forward of the beam, the pics were linked somewhere on catsailor

the nacras have very long bows and that length means big leverage on the unsupported bows

search for some pics of the team phillips trimaran for similar long unsupported bows being stressed beyond what the designer expected