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PostPosted: Sat Aug 08, 2009 4:29 pm 
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Joined: Thu Jul 30, 2009 12:17 pm
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Location: Homosassa, Florida
This is a sink/flotation test of a Hobie Adventure

One person – Age 62, Weight 170 lb, no experience in kayaks, 50 years experience on or in the water.

Vessel - Hobie Adventure without any equipment on board

Equipment - 1 noodle, 1 West Marine hand pump 16 inches (throw away outlet hose), 1 inflatable lifejacket

Environment – one pool, fresh water, 89 degrees, calm seas (no swell, no breaking waves, no chop, no boat wakes)

First test – What it takes to sink the kayak.
At first I rolled the kayak and left it upside down for 5 min. Righted, boarded and checked for water in hull. No water entered hull.
Second removed bow hatch and rolled kayak and left upside down for 5 min. Righted, boarded, and check for water in hull. About 1 gal in hull. Removed with sponge.
Third removed bow hatch, opened midship hatch, and opened stern hatch. Rolled kayak and left upside down for 5min. 1 min after rolling the kayak settled about 4 inches in the stern and then stabilized. Closed all hatches with kayak upside down then righted, boarded and checked water in hull. About 5 gal in hull. Removed with pump.
Duplicated third test without closing hatches before righting. With hatches open righted kayak. Kayak submerged with 1 min of righting. Appeared to still have some small pockets of air in hull.

Second test - What flotation is needed to prevent sinking.

With kayak under water with hatches open I put one 4 inch noodle in the bow. One noodle provides approximately 30 lbs of lift. Kayak floated with bow out of water.

Third test – What does it take to completely dewater the kayak.

I closed the midship and stern hatches. The front hatch was still not clear of the water. I repositioned the noodles slightly towards the stern and got the bow hatch cleared water line. However, any weight I put on the hull pushed it below the waterline. I could not operate the hand pump and tread water. I inflated my life vest and was able to operate the pump without putting weight on the hull. After 10 min of pumping I was able to gain enough flotation to put some weight on the hull. It took 10 more min of pumping to raise the kayak enough to board and have the midship hatch clear of the waterline. (Waterline was 1 ½ inches below the mold line on the kayak). I opened the midship hatch and pumped 5 more min. Then, moved to the stern hatch and pumped the rest of the water out. Total dewatering 30 min.

Conclusions:

At least 30 lbs of lift is needed to keep the Adventure from completely sinking. In my opinion about 50 lbs of lift would be wise if you are going to venture out of your pool. This lift will prevent you losing the kayak even if the hull is punctured. A standard cheap lifejacket provides about 25 lbs of lift and the Hobie gear bag with only air provides about 20 lbs of lift.

If you do turn over with any hatches open, close them before righting the kayak. The kayak won’t sink while upside down, in a calm sea, with no breach in the hull.

The kayak cannot be dewatered without enough floatation to get one of the hatches clear of the water. It is extreemly difficult (even in a perfect enviroment) to pump without touching the kayak. The bow hatch is the only one that I could get clear of the water with the amount of floation I used.

It is difficult to reboard the kayak with the hull over 1/3 full. Any their is no way to pump water out with the hull over 1/3 full. Pumping is a lots easier inside the kayak.

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PostPosted: Sat Aug 08, 2009 7:35 pm 
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Joined: Sun Aug 02, 2009 11:29 am
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so, is the answer to stuff as many pool noodles as you can cram in the hull to make the yak float better while full of water?


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PostPosted: Sat Aug 08, 2009 8:44 pm 
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Joined: Sat Nov 12, 2005 10:46 pm
Posts: 2362
Location: Escondido
Ranger, excellent test and very good information to have! I better get a few pool noodles and lash them in place, as well as a bilge pump just in case. It's a small price to pay to prevent the possible loss of a kayak (and my ride back to shore). :wink:

PS Was the Mirage Drive in or out?


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PostPosted: Sun Aug 09, 2009 4:32 am 
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Joined: Thu Aug 16, 2007 2:25 pm
Posts: 1869
Location: Central Coast NSW Australia
Great test Ranger! 8)
I have always carried a couple of pool noodles after reading some very early posts recommending them but your experiment may be the first that provides concrete evidence.
Thanks for posting! :)


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PostPosted: Sun Aug 09, 2009 4:54 am 
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Joined: Thu Jul 30, 2009 12:17 pm
Posts: 164
Location: Homosassa, Florida
The drive was not in the kayak. I didn't want to risk any damage to it from the pool bottom.

Actually, I am leaning towards some sort of closed cell foam that would be shaped to the bow. I also looking at something that would have duel use. Two cheap lifejackets provide the necessary floatation but retain water when wet and would be a mess after a while it left in the hull.
Remember the noodles have to be 4 inch in dia. and have to be in the bow.


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