Capsizing and anti-turtling inflatable device

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Capsizing and anti-turtling inflatable device

Postby willyhays » Thu Aug 14, 2014 7:18 pm

Ahoy fellow Day Sailer Sailors,
I am considering buying an anti-turtling device. It's an air bag that attaches to the mast. It automatically inflates following a capsize.

They are made in Germany by Secumar (‪www.secumar.com). There is no retail source in the USA, so they must be special ordered. There is a distributor in Miami that will order them for $324.00 each. If we order 5 of them at one time they'll give a 5% discount. Delivery time is 4-6 weeks. The distributer is http://www.datrex.com

http://www.secumar.com/secumar/php/main ... ukte&id=77

If the link does not work you can google: secumar anti-inversion cushion

Anyone interested?
Last edited by willyhays on Fri Aug 15, 2014 2:56 pm, edited 1 time in total.
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Re: Capsizing and anti-turtling inflatable device

Postby jkfinity » Fri Aug 15, 2014 11:49 am

The product link that you tried to provide is cut off, and can't see anything.
John / Burlington Vermont / Lake Champlain
1973 DS II # 6216 "Suluhu"
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Re: Capsizing and anti-turtling inflatable device

Postby willyhays » Fri Aug 15, 2014 2:58 pm

Thanks jkfinity for pointing out the broken link! Hopefully the new link will work, otherwise you can google: secumar anti-inversion cushion.
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Re: Capsizing and anti-turtling inflatable device

Postby GreenLake » Fri Aug 15, 2014 4:38 pm

Looks like the link works now.

Here are my personal thoughts on the device. It's a nifty idea that could allow significant flotation at the mast top with limited windage, because the compact size of the device prior to inflation.

The smaller of the two devices gives > 5gals of flotation. That would seem enough for the DS. A catamaran might need more. (I base the estimate on the fact that it would take about 5gals of water to balance the hull on the hard, that is hold the mast horizontal with the weight of the hull suspended on a gunwale. It would seem that this is a good approximation of the magnitude of forces that would act to turtle a boat that has capsized).

The device represents significant weight, which, positioned at the end of a long lever arm will require between 5-10 lbs of additional crew weight to balance (50% more for the larger size). In addition to the weight of the device comes the weight for the recommended dedicated halyard and halyard block. (I remember having done the exercise once and come with a ratio of between 1:5 and 1:10 at 30 degrees of heel. Feel free to re-calculate and correct).

The price quoted for European customers is € 149.00, and includes 19% VAT which is not due on export, the US price of $324 comes to €240.00 at today's exchange rate, and presumably does not include tax. Subtracting the European tax, the US price seems to allow for a markup of $100.00, which is a bit steep. Even if the quoted price included shipment from Europe, there seems to be a considerable markup over the end-user price.

One downside that I see is based on the active nature of the device: it comes with a significant need for maintenance. The instruction manual suggests to check the trigger for device each time it is used and another, more extensive check every season. Finally, every two years, you are supposed to send the unit in for service.

It seems that a floatation pouch attached to the top of the sail and / or some foam attached in front of the mast top (aerodynamically shaped) would result in a passive system of comparable or better characteristics as far as flotation benefit and costs in terms of windage. With the added benefits of much less expense and that it would be an "install and forget" solution.

My 2cents.
~ green ~ lake ~ ~
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Re: Capsizing and anti-turtling inflatable device

Postby jeadstx » Fri Aug 15, 2014 5:09 pm

I use foam flotation in the top 2 feet of my mast. I capsized in 2012 and the masthead stayed on the surface and the boat stayed on it's side. Later when taking down the mast I found mud/sand in the masthead which meant the mast hit bottom (I was in 6 -7 feet of water), but the flotation in the masthead allowed the masthead to come back to the surface instead of sticking in the bottom and potentially damaging the mast.

John
1976 Day Sailer II, #8075 - Completed the 2011, 2012, and 2013 Texas 200
1952 Beetle Boat Swan Catboat
Early Rhodes 19
1973 Mariner 2+2, #2607 - Completed 2014, 2015 and 2016 Texas 200
1969 Day Sailer I, #3229
Fleet 135; Canyon Lake, Texas
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Re: Capsizing and anti-turtling inflatable device

Postby willyhays » Sat Aug 30, 2014 1:50 am

Thank you both for your comments. I appreciate all the feedback. Some good food for thought. No question, the price is awfully high. I also found some interesting comments questioning the wisdom of any type of anti-inversion flotation. The concern being that some types of boats on their sides may blow downwind faster than a person in the water can swim. Whereas an inverted boat will drift very slowly.
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Re: Capsizing and anti-turtling inflatable device

Postby GreenLake » Sat Aug 30, 2014 10:31 am

How fast can you swim?

The DS weighs about 600 pounds and when the sails are in the water, that's not insignificant friction.

So, I'd be curious to know how fast it would go?

Depends a bit on the wind.

Wonder if anyone here has actual experience.
~ green ~ lake ~ ~
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Re: Capsizing and anti-turtling inflatable device

Postby jeadstx » Sat Aug 30, 2014 12:55 pm

When I capsized, the wind was about 15 plus knots. The boat did drift some, but not fast enough to lose it. You can grab a line.

John
1976 Day Sailer II, #8075 - Completed the 2011, 2012, and 2013 Texas 200
1952 Beetle Boat Swan Catboat
Early Rhodes 19
1973 Mariner 2+2, #2607 - Completed 2014, 2015 and 2016 Texas 200
1969 Day Sailer I, #3229
Fleet 135; Canyon Lake, Texas
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Re: Capsizing and anti-turtling inflatable device

Postby curifin » Sat Aug 30, 2014 7:54 pm

My capsize, turtle, and aided recovery was in about 7-10 knots sustained, gusting to mid 20s. Drift was not a problem. I wished I had installed an anti-inversion device. Subsequently, I purchased, but have not installed, a Hobie bob. I have gotten a lot better at controlling the boat and simply have not felt the need for it now that I have a properly reffing mainsail and better skills.
1970 DS1 "Denial"
1993 Beneteau First 210 "Dory"
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Re: Capsizing and anti-turtling inflatable device

Postby willyhays » Sun Aug 31, 2014 10:39 am

Sounds like drift might not be that much of an issue with the Day Sailer. The posts I read about drift did not identify the dinghy. Might have been a boat that is much lighter than the Day Sailer.

Last weekend I hoisted ten one-gallon milk jugs up the jib halyard, then capsized the boat. The boat stayed comfortably on its side with the milk jugs on the surface. I got in the water and pushed down on the mast. It went down easily, but popped right back up to the surface when I relieved the pressure. I was able to right the boat with very little effort.
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Re: Capsizing and anti-turtling inflatable device

Postby GreenLake » Sun Aug 31, 2014 10:58 am

Now for the same experiment with 9, 8, 7, ... or 1 milk jug.

What's the minimum amount of flotation needed? Is it really 10 gallons?
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Re: Capsizing and anti-turtling inflatable device

Postby willyhays » Mon Sep 01, 2014 8:51 am

I have no doubt that 10 gallons is more, probably much more, than what is needed to resist inversion in most situations. When I have more time I expect to do a more thorough experiment, per your suggestion, i.e., 9, 8, 7, etc. To determine the minimum amount needed could be very useful.

Two factors led me to select 10 gallons. The first is that I want the float to be at the hounds rather than the masthead. The second is that I want a very large margin of safety. This is because I'll be beach cruising on the coasts of British Columbia and Alaska far from any assistance in very cold water and exposed conditions. An inversion during this trip could very well make it my last.
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Re: Capsizing and anti-turtling inflatable device

Postby GreenLake » Mon Sep 01, 2014 11:22 am

In those conditions, you really ought to wear a full-body wetsuit, or a dry suit. Even if the boat doesn't turtle, you might not last long enough without one to right it again. In areas with very cold waters, summertime can be the most problematic, as the protective clothing can be too warm to be comfortably worn given the prevailing air temperatures, yet the water remains cold.

What is so magical about not having the flotation at the masthead?

If you are worried about weight, it's the same lever. By going up, you need less flotation, and therefore the weight goes down. As a result, the effect on balance remains the same.

The effect for windage should similarly go down with less flotation, and the heeling contribution from that windage should therefore be (roughly) constant where on the mast you place it. The component that results in drag would reduce if you went to the mast head, because the overall windage is less, and for drag, the effect does not depend on the lever arm.
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Re: Capsizing and anti-turtling inflatable device

Postby willyhays » Tue Sep 02, 2014 10:48 am

The spar is highly tapered. I want to avoid undue loading on the tapered section. This may be not be an issue in a capsize in moderate conditions, but could be in rough conditions. My intention is to minimize wear and tear and the risk of damage.
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Re: Capsizing and anti-turtling inflatable device

Postby GreenLake » Tue Sep 02, 2014 11:50 am

I'm not expert enough to predict the dynamic loads on the mast tip (in its natural state with sails rigged) when a boat capsizes. Initially, the main will resist being pushed under water, and that should lead to significant dynamic loads as the mast tip hits the water. Also, if the boat is moving forward, it would drag the tip through the water until it comes to a stop. The static loads from a few gallons of flotation may not be significant by comparison, but then there might be dynamic load from additional drag. Complicated picture.
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