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Hull Flex - serious concerns http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=2658	Page 1 of 1

Author:	fury [ Sun Nov 06, 2005 4:38 pm ]
Post subject:	Hull Flex - serious concerns
Hi, I am setting up an old 16 for some higher wind, rough water sailing. Thare was some delamination in the fordeck areas, which has been repaired, and certainly more stable than before. However, there are also large inspection ports , in the decks , just forward of tramp and I am wondering if this has weakened the structure. There is a lot of flex in the nose area, the 2 hulls are pulling together under the strain of the forestay, about 1 - 2 inches. The noses also lift up by about the same amount under high load. any thoughts .... any one. We lost the forstay on the weekend, causing the entire rig to collapse. This is not a good thing , but probably saved causung severe damage to the hulls. Please dont post - get new hulls, I dont have the money. I just enjoy flying a hull in a stiff breeze, thanks everyone

Author:	richandpat [ Sun Nov 06, 2005 5:59 pm ]
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You might try attaching a piece of wood across both bows attached at the Bow Tangs with a long bolt (or screw) - just like the old P Cats (Pacific Catamarans). That should keep the hulls from pulling together under the strain of the forestay. Good luck! Richard

Author:	fury [ Sun Nov 06, 2005 6:20 pm ]
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I did have a piece of 1"alloy tube, between the hulls at that point, but was suprised when it bent into an arc I removed it and the hulls sprung back. It also caused a horendous amount of spray when the nose was in the water. ( so I couldnt see, unless on the trap) I am going to lengthen the bow strops (from each bow) to decrease the angle of side ways force. looking at other 16 photos, these strops are at a very horisontal angle, compared to others. Hopefully, that will help ths side ways problem a bit, but not the "upwards" problem. I also have a alloy tube from each nose, to the tramp corner mounts ( like a compression post ) Even these tend to bow a bit... I didn't want to put too much weight up there either. ... any one else have some suggestions ? Thanks

Author:	Hobie Nick [ Mon Nov 07, 2005 6:56 am ]
Post subject:
When you increase the bridle wires on the bow, you will change the length of the forestay and will probably interfere with the jib sail. If you are able to afford some fiberglass repair work, I would reccommend reinforcing the hull ports. This will allay your fears and help some with the flex in the hulls. Just out of curiosity, how much wind are you sailing in and how much is the crew weight? I'm a pretty big guy and have sailed H16's in 30 kts steady and never had such a severe hull fles problem. I also had the ports in my boat.

Author:	fury [ Mon Nov 07, 2005 7:30 am ]
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I had a long strop to extend the forstay, but obviously someone had changed this from original. I had it rigged today and measured the flex accurately, which was over 4 1/2 " sideways, and estimated 2 - 3" up. The forstay should b ethe right length, thus taking the strops back to original. I estimate each strop to be 4 foot long each. Wind strength would be constant 20 to 25 with gusts to whatever. seas to 3 - 4 feet ( 1.2 mts) skipper weight 15 + stone / 105 kg, with light, slender lady crew lots of fun

Author:	MBounds [ Mon Nov 07, 2005 9:06 am ]
Post subject:
Quote: Wind strength would be constant 20 to 25 with gusts to whatever. seas to 3 - 4 feet ( 1.2 mts) skipper weight 15 + stone / 105 kg, with light, slender lady crew You're stressing the boat pretty hard in those conditions - especially with 300+ lbs of people on the boat. I've seen relatively new boats break in less. You need to keep an eye out for transverse stress cracks in the deck forward of the front pylons - especially where your ports are. You could reinforce the outer deck lip to give you some added strength in that area - just flip the boat over, clean the underside of the deck lip really well, then lay 1 meter long strips of fiberglass tape that have been wetted out with epoxy resin. Go from just aft of the front pylon forward. That's the highest stress area. When (not if) the hull breaks, it'll snap off just forward of the front pylon. If you're getting that amount of flex, it's only a matter of time.

Author:	fury [ Mon Nov 07, 2005 2:26 pm ]
Post subject:
Have you ever ( has anyone ) actually seen a hull snap at that point? Quote: I've seen relatively new boats break in less. :shock: There are some gelcoat cracks in this area. Does it give any warning or just goes "BANG" ? Any info on this is appreciated.. Quote: If you're getting that amount of flex, it's only a matter of time. That does give me some major concerns. I must admit, I don't want to be out to sea, if this happens with the wong conditions. Once again, Thanks everyone, Chris

Author:	MBounds [ Mon Nov 07, 2005 5:45 pm ]
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This one gave no warning: That was a 10 year old boat - relatively new as Hobie 16's go. The beer can in the hull is a nice touch. This one took a tumble down the beach in a wind storm - but it was a relatively new boat and should have been able to withstand it. Notice that it broke in the same place:

Author:	Hobie Nick [ Tue Nov 08, 2005 6:17 am ]
Post subject:
It makes sense that the hulls would break there. You have 1/3 of the hull cantilevered and taking some serious stress from the forestay.

Author:	fury [ Tue Nov 08, 2005 3:15 pm ]
Post subject:
OUCH I think I'll be doing some hull reinforcement in that area... I like the gunwhale strengthening idea. Perhaps integrating some carbon fibre / kevlar or rovings would help and just flush finish to the gunwhale edge (so there is no hollow / concave section - under the gunwhale, where you would lift from) I have been sailing / competing for years and have the titles that go with that commitment, but this is my first 16 and not used to it's unique problems. Thanks for your thoughts and photos. I value your continued imput. Thanks again

Author:	Jeff Peterson [ Thu Nov 10, 2005 1:34 pm ]
Post subject:
Keep us informed. We all love a good disaster story, if no one gets hurt. And take pictures of all the broken stuff to post here. Seriously, you need to replace your hulls. Since you know the future holds impending doom, start looking now for that good deal on used hulls. If you are patient, the deal will come to you. I feel for you. My old Hobie probably has about two years left in it, before its bait for used-parts scavengers. I've repaired deck delaminations on both hulls. I have some flex, but nothing like the flex you describe.

Author:	fury [ Thu Nov 10, 2005 7:26 pm ]
Post subject:
I hope it wont end in a disaster story, as I am usually carefull with what i am doing. I do intend to reinforce the hulls, before I do anything too crazy. I am supprised at the speeds that these things getup to. I logged on my gps 39 kph, and that was during a slowish patch (when I was inboard and with a spare hand to take a look) The bows flexing (up and down + in and back out in the puffs) was surely the most off putting part of the whole sail. The pressure on the forstay / bridal assembly, really made me think about the strain that these things are under. The bows were just starting to lift out of the water and I was bearing away under some heavy accelleration, when the swage on the forstay extension let go and the whole rig came crashing down. It Would have been the start of the fastest run of the day.... But there is allways next week ! This thing's a blast !!

Author:	fury [ Fri Nov 25, 2005 3:49 pm ]
Post subject:
UPDATE After doing some of the suggested repairs, the hulls have stabalised to a point I would consider normal. I ended up filling the lip on the underside of the gunwhales , on outside of edges of the hulls, from the side stay points - forward. I used woven mat, rolled in a "tight tube", with polyester resin, rather than epoxy. I didn't fill to the top, but feathered the ends, so as not to create a weak spot. This has helped the bows from comming together particularly. I have also changed the forstay bridle , so it is not as "flat" but now seems more like in photos of newer boats - obviously changing the load angle. Has been out in 20Kn , 1 capsize ( 2 min) and 1 turtle ( five minutes) and lots of extreeme fly-buys The whole exercize, was worth it and feels much stronger Thanks for your imput Chris

Author:	pappastratos [ Sat Apr 29, 2006 11:11 pm ]
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I saw a post where a person put the 2 part expanding marine foam in the forward areas of the hulls. see: http://www.hobiecat.com/community/viewtopic.php?t=2051 Sounds real good, I would suggest doing it in smaller amounts until area is filled.

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