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Buoyancy Issues in Desperate Need of Help!
http://www.hobie.com/au/en/forums/viewtopic.php?f=17&t=10446		 Page 1 of 2
Author:  Cameron [ Thu Aug 21, 2008 11:51 am ]
Post subject:  Buoyancy Issues in Desperate Need of Help!
Hi all, have been reading this forum for the past couple of months but only just signed up. I've had a couple of problems with my Hobie 14 Turbo since I got it in May, the latest being the starboard rudder ripping off (twice in two weeks, now solidly back on...I hope).

Here's a few photos of me out playing (im in red), I know there are two of us on the boat but the hulls sink a lot anyway with just me on it and to be honest i don't think they should this low with me and a teenager on it!

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I really need advise on how to sort the buoyancy issue because it's highly frustrating, slowing me down, making me nervous, stopping me from taking the boat into rough seas (if you can call 2 metre swells rough seas) and it has caused me to flip and go turtle a couple of times (all the boats fault...).

If anyone notices any other problems with it please tell me because there are no other 14 Turbos near me to compare too.

P.S. Please excuse the bottles at the top of the mast, they have been replaced by an inflatable 25L dry bag which has yet to be tested (I can't afford a Bob).

Thanks for your help.

Cameron
Author:  MBounds [ Thu Aug 21, 2008 12:45 pm ]
Post subject: 
A 14 is a single person boat. If you put more than one person on it, it's going to be low in the water. Period. The only thing you can do is check the weight. The boat with all it's rigging / sails should be about 115 kg (little more than 18 stone)

I'd call 2 meter waves rough seas. They're taller than you are.
Author:  Cameron [ Thu Aug 21, 2008 1:15 pm ]
Post subject: 
[quote="MBounds"]A 14 is a single person boat. If you put more than one person on it, it's going to be low in the water. Period. The only thing you can do is check the weight. The boat with all it's rigging / sails should be about 115 kg (little more than 18 stone)

As I said, its still low in the water when its just me, when I get some light down the hull it looks as if there isn't any foam in there.

I would really appreciate some technical help with the buoyancy issue.

Unfortunately my club doesn't have any gigantic boat scales and I am unable to take it to the nearest lorry weigh in station; please advise.
I highly doubt there is any extra weight on it as there is nothing visible and I can't imagine the previous owner filling the mast with lead.

I hate to sound ungrateful for your comments Mr Bounds, but I would have hoped a man of your expertise would be able to provide more advise than just have one person on the boat and check your boat isn't heavier than it's meant to be.

Sincerely

Cameron
Author:  MBounds [ Thu Aug 21, 2008 2:11 pm ]
Post subject: 
You wanted technical advice - I'm about as technical as you can get.

I'm a naval architect. University of Michigan '82. I've also owned a Hobie Cat since 1973 and currently own 4 - including a 14. I've raced them for 35 years and have two North American Championships to my credit.

Bouyancy has nothing to do with what's in the hulls. Bouyancy has everything to do with how much water the hulls displace, which equals how much it (and the people that are on it) weigh.

A Hobie 14 is a Hobie 14 - the hulls are the same shape the world over and will float at the same level if they weigh the same. If the boat is too low in the water, either it weighs too much or you're putting too much weight on it. It's that freaking simple.

Foam in the hull makes the boat heavier and will make it float lower, not higher.

Weighing the boat doesn't have to be that complicated. Put it on two cheap (mine cost $6 each) bathroom scales (one under each hull roughly where the shrouds attach) and add the weights together. Do it on a flat, hard surface, like a parking lot.

Unfortunately, if the boat weighs a lot - and I've seen some that do - there isn't a whole lot you can do about it.

If there's not something obvious (like gallons of water in the hulls), then my advice is to stop worrying about it and go sailing.
Author:  Cameron [ Thu Aug 21, 2008 4:17 pm ]
Post subject: 
Thank you.

I appreciate you are one of the best that is why I was a bit taken aback by your original reply, I apologise if I may have been a bit short.

So, I get a couple of bathroom scales and its overweight, where should I look to reduce weight?

There were comments made about this boat sitting low on one side
http://img233.imageshack.us/img233/8775/img3063ip6.png
I would be over the moon if mine sat that high even on the low side!
Author:  Geoff [ Thu Aug 21, 2008 4:41 pm ]
Post subject: 
I would suggest put the boat on the water fully rigged without anyone on it, and measure the height from the water line, at the point where the shrouds attach, up to the lip of the hull, and post that here. Someone here should be able to measure their boat and compare. Mine is out the water for the winter.

If you are wanting to lighten it, you could leave off the jib. Also check the battens, if they are standard, although the non-standard ones I have seen weighed less. I would expect a six batten sail to weight more than a five, but can't say I have ever heard anyone be so concerned about bouyancy. I would suspect some hulls would be heavier. I think hulls were locally manufactured. But it would have been a largely by hand thing, so they would have to vary.
Author:  Rick Buchanan [ Thu Aug 21, 2008 4:51 pm ]
Post subject: 
The buoyancy of your boat, or any object is easy to figure out... It's how a Boeing 747 can get off the ground which has me amazed!
Main Entry:
buoy·an·cy Listen to the pronunciation of buoyancy
Pronunciation:
\ˈbȯi-ən(t)-sē, ˈbü-yən(t)-\
Function:
noun
Date:
1713

1 a: the tendency of a body to float or to rise when submerged in a fluid b: the power of a fluid to exert an upward force on a body placed in it; also : the upward force exerted
Archimedes Principle states that the buoyant force on a submerged object is equal
to the weight of the fluid that is displaced by the object. ...
Author:  hobiekatz [ Fri Aug 29, 2008 1:11 pm ]
Post subject: 
Cameron wrote:
Thank you.

I appreciate you are one of the best that is why I was a bit taken aback by your original reply, I apologise if I may have been a bit short.

So, I get a couple of bathroom scales and its overweight, where should I look to reduce weight?

There were comments made about this boat sitting low on one side
http://img233.imageshack.us/img233/8775/img3063ip6.png
I would be over the moon if mine sat that high even on the low side!


That's my Hobie in the picture you quoted. That was the first day i had it in the water. When i bought it, the previous owner had sealed the plugs with removable silicone and when we drained it it had aprox. 1-2 liters of water in each hull after that day which included 2 turtles. From the picture i can tell you that it is the wave that make one hull look lower than the other. we turtle the boat twice that day so i can't say if the water was from us or the previous owner. i can say that since then we have sailed it aprox. 8 times with 2 turtles and the amount of water in each hull was aprox. 1/4 liter or less in each hull. i have a 1982 hobie and was told it weights aprox. 265lbs???

it looks like you weight about 160lbs and with your friend i'd say he weights 130lbs. here is a picture of me and my dad, aprox. 340lbs and probably 1-2 liters of water in each hull on a gibe. Our rear ends were under water...

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Author:  Triggs [ Sat Aug 30, 2008 6:47 am ]
Post subject: 
I sail a 14. I am about 185lbs. I can tell you the 14 is very weight sensitive. If I sit too far back in light wind the windward rear hull will actually submerge. If you shift your weight far enough back you could almost do a reverse pitchpole. From the looks of the photos it is simply too much weight on the boat. The 14 is a fantastic single handed boat! Put it in the water and sail!
Author:  Triggs [ Sat Aug 30, 2008 6:49 am ]
Post subject: 
hobiekatz, Noticed you are in Southern Ontario. Ever get out to Fanshawe? There is a number of Hobie Sailors out there.
Author:  biiggd [ Mon Sep 01, 2008 4:42 pm ]
Post subject:  Hobie 14 sitting too low in the water?
Thanks to all who responded to this problem of low bouyancy for the Hobie 14. I have been concerned likewise that my 14 sits too low, but comparing the pics that were submitted by viewers, mine sits exactly the same as the other boats in the submitted pics. I think it is the nature of the beast and is due to the profile of the nice, thin, efficient hulls that Hobie originally designed for his cats. My thinking is, however, this very problem of low bouyancy is the reason he designed the Wave, Breeze, And Getaway with the fat hulls....sacrifice sleekness and a little speed for more bouyancy to accomodate today's heavier sailors! Was a good move from a marketing standpoint. I recently sailed a Wave for 4 hours with 3 150 pounders on board and it sat very high in the water...twice as high as my Hobie 14! This makes the Wave a much more versatile and marketable boat! But I still love the 14 for what it is...a one man boat@!
Author:  hobiekatz [ Mon Sep 01, 2008 7:58 pm ]
Post subject: 
Triggs wrote:
I sail a 14. I am about 185lbs. I can tell you the 14 is very weight sensitive. If I sit too far back in light wind the windward rear hull will actually submerge. If you shift your weight far enough back you could almost do a reverse pitchpole. From the looks of the photos it is simply too much weight on the boat. The 14 is a fantastic single handed boat! Put it in the water and sail!


+1

Triggs wrote:
hobiekatz, Noticed you are in Southern Ontario. Ever get out to Fanshawe? There is a number of Hobie Sailors out there.


not yet...next year most likely. that's by London correct?
Author:  Triggs [ Tue Sep 02, 2008 6:57 pm ]
Post subject: 
hobiekatz. There's lots of stuff going on in the area. Shoot me your email address and I'll give you all the details. [email protected]
Author:  xanderwess [ Tue Sep 02, 2008 7:16 pm ]
Post subject: 
Hahahaa..........so, you think your boat sits too low in the water........too heavy, not enough flotation. You don't know heavy boats. You have no idea. My boat is 50 lbs over min. weight, and thats the way it goes..........I am not even a fat man, but yet I consistantly weigh in one of the top 5 heaviest sailors at the 14s year after year..............(I got nothing to say about the 2m waves though, thats some pretty rough (censored) there.) If you're worried about floatation and the way the boat looks in the water, then get rid of the real man's boat (14) and get one of those chicken (censored) 18s or getaway or something.
Sailing a 14 in a blow, thats a MANS GAME. Like rugby, only not as sissy. Aaarrggghhh.
Author:  pbisesi [ Wed Sep 03, 2008 4:56 am ]
Post subject: 
Like Mr. "Nuclear" Wessels says.
In a blow the 14 is a handful.
I tip the scale at 220 and watch the lea hull disappear on a regular basis.

Image :shock:
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