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Thread: shellback capsize

  1. #1
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    Default shellback capsize

    i'm building a shellback dinghy and the forum has been very helpful with the many questions I've posed.

    here's an interesting one. I'm building this boat for my niece and nephew and they have a three year old son. The boy will of course be wearing a life preserver, but still if the boat flips and fills with water I'm wondering if it will stay afloat, at least enough to sit in it with water up to the rales, and not go down. If not, do you think that if I install compartments under each seat and fill with flotation foam I would achieve this measure of safety?

    tough question, but you are all very SMART guys ( and perhaps some gals?)

    david

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    Default Re: shellback capsize

    Quote Originally Posted by dposner View Post
    i'm building a shellback dinghy and the forum has been very helpful with the many questions I've posed.

    here's an interesting one. I'm building this boat for my niece and nephew and they have a three year old son. The boy will of course be wearing a life preserver, but still if the boat flips and fills with water I'm wondering if it will stay afloat, at least enough to sit in it with water up to the rales, and not go down. If not, do you think that if I install compartments under each seat and fill with flotation foam I would achieve this measure of safety?

    tough question, but you are all very SMART guys ( and perhaps some gals?)

    david
    If you do this

    site:http://forum.woodenboat.com/ "dinghy flotation"

    in your search window, you'll get a list of threads discussing flotation. Here's one:

    http://forum.woodenboat.com/showthread.php?202695-Shellback-Dinghy-100lbs-of-buoyancy-bags-enough

    Hope the voyage is a long one.
    May there be many a summer morning when,
    with what pleasure, what joy,
    you come into harbors seen for the first time...

    Ithaka, by Cavafy
    (Keeley - Sherrard translation)

  3. #3
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    Default Re: shellback capsize


  4. #4
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    Default Re: shellback capsize

    Quote Originally Posted by dposner View Post
    i'm building a shellback dinghy and the forum has been very helpful with the many questions I've posed.

    here's an interesting one. I'm building this boat for my niece and nephew and they have a three year old son. The boy will of course be wearing a life preserver, but still if the boat flips and fills with water I'm wondering if it will stay afloat, at least enough to sit in it with water up to the rales, and not go down. If not, do you think that if I install compartments under each seat and fill with flotation foam I would achieve this measure of safety?

    tough question, but you are all very SMART guys ( and perhaps some gals?)

    david
    This is how high a stock Shellback floats when swamped:
    capsized shellback.jpg

  5. #5
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    Default Re: shellback capsize

    I am a very strong believer that if I take someone new out sailing I make it as risk free, safe feeling and enjoyable as possible. The point at which someone new to sport becomes stressed will be very different to that of an experienced person. A swamped boat just afloat will not feel very safe to a novice.

    Although they are called buoyancy bag/tanks such volumes have an equally important job other than just providing buoyancy. They need to be keeping the swamped boat stable and minimising the amount of free water in the boat so reducing bailing. If you look at modern dinghies they are all doing this.

    Fit as much buoyancy as you can using inflatable bags, especially along the sides. When you go out by yourself for an evening cruise you can remove them and rely on some foam under the seats

    Someone safely taught you to sail, you have an obligation to our great sport to do the same, scaring people through poor planning is not acceptable.

  6. #6
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    Default Re: shellback capsize

    Quote Originally Posted by DGentry View Post
    This is how high a stock Shellback floats when swamped:
    capsized shellback.jpg
    That strikes me as an unfinished boat design.

  7. #7
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    Default Re: shellback capsize

    In the 10 ft sailing dinghy I designed and built for our cruising in Drake, I ran the seat fore-and-aft, as per Bolger. (I much prefer this for boat trim. With 2 sets of oarlocks, and the long seat, you can be perfectly trimmed for 1, 2 or 3 people.) Under it I glued a 2" slab of pink foam, full length.

    I only swamped it once, as a test, at a beach. No photos. The foam plus the encapsulated wood kept the gunwales just above water as long as I wasn't in it. So theoretically you could reach in and bail. But it would take forever, and any waves would wash in and negate your efforts.

    None of these open boats are good when swamped. Better to not swamp.

    More important is to have easy-to-use reef points in the sail. And don't cleat the sheet. And sail on only nice days.
    Attached Images Attached Images

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    Default Re: shellback capsize

    Quote Originally Posted by Clarkey View Post
    That strikes me as an unfinished boat design.
    That strikes me as a submarine ...

  9. #9
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    Default Re: shellback capsize

    It looks to me as though that fellow is actively holding his Shellback down. His torso is half out of the water. It shouldn't be too hard to add enough flotation to make the boat rescuable by its crew.

  10. #10
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    Default Re: shellback capsize

    Quote Originally Posted by Rob Hazard View Post
    It looks to me as though that fellow is actively holding his Shellback down. His torso is half out of the water. It shouldn't be too hard to add enough flotation to make the boat rescuable by its crew.
    Indeed but shouldn't that be the job of the designer?

  11. #11
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    Default Re: shellback capsize

    One could certainly argue that point, but Joel White passed away 20 years ago.
    Maybe a stock Shellback can be rescued by her crew provided that they are actually trying to dewater her, rather than trying to hold her underwater. The same could be said of most open river canoes.
    If you're looking for a boat that you can simply right, climb in, and sail away, maybe what you're after is a Scamp, or a Laser.

  12. #12
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    Default Re: shellback capsize

    Although plywood, the hull itself still has buoyancy. My gut says that it has enough buoyancy to float higher than this shown in the photo, so I second Rob.

    According to quick/unofficial calcs, the Shellback needs 2 cu ft to be self rescuable if the DB trunk is completely sealed and more to really be sure the top of the trunk is above to swamped waterline.
    Clinton B. Chase
    Portland, Maine

    http://tinyurl.com/myboats

  13. #13
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    Default Re: shellback capsize

    Adding positive buoyancy strikes me as a relatively modern addition. I would have to guess that in the past there was a bit less worry about ultimate safety (possibly because the designer stood less of a chance of getting taken to court by the relatives of some hapless sailor) and because being made of wood most un-ballasted boats wouldn't head straight for the bottom when swamped.
    Steve

    Boats, like whiskey, are all good.
    R.D Culler

  14. #14
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    Default Re: shellback capsize

    The open design keeps the Shellback pretty versatile and light weight.

    I added flotation on mine for various reasons.



    Works great for me. Daggerboard trunk stays about 2-3 inches above flooded area, easy for me to self recover. However, you can see that the forward seat is no longer a seat. It's heavier and may not be the greatest layout for everyone.



    Aft flotation works fine both as a seat and float. You could do something similar to the front. It does add weight though.


    If you want to keep it light weight and versatile, you could just add float bags like this:



    Whatever floats your boat.

    Travis.

  15. #15
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    Default Re: shellback capsize

    Love the Shellback, one day would like to build one and I would add minimal buoyancy to keep the uncluttered inside for my personal use. We are not talking about one person being able to get back in a swampt boat we are talking about a 3 year old still sailing when he is 10, 15, 20......... and not being scared to death and never leaving the comfort of his video screen.

    may be ranting, just in from a two day intense Race Sail coaching course

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    Default Re: shellback capsize

    I've been working on the same issue with my Whisp. Alterations and tests in this thread. At this point, I'm with a combination of built-in buoyancy and float bags. At the very least, I'd put some foam under the thwarts in the Shellback so that body weight alone does not drive it totally under. Varnished trim panels can hide the foam nicely.
    -Dave

  17. #17
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    Default Re: shellback capsize

    I stuff flotation bags under the seat

    oops,wrong picture.
    Old seats from dead zodes. They are very tough.Ask inflatable repair places if they have a few. Pay no attention to the plastic jugs.

    This is my warm water dingy of course. Trick is to practice before it is too late.
    Last edited by wizbang 13; 10-31-2017 at 09:29 AM.

  18. #18

    Default Re: shellback capsize

    I think it is time to post this link again http://sailingcatamarans.com/index.p...os-talk-at-wbf

    All small boats should have sufficient buoyancy not just to stop the boat sinking, but to float approximately level and support the weight of the crew. That is a legal requirement for small boats in Europe, so makes sense elsewhere as well

    Richard Woods of Woods Designs

    www.sailingcatamarans.com

  19. #19
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    Default Re: shellback capsize

    Quote Originally Posted by Richard of Woods Designs View Post
    I think it is time to post this link again http://sailingcatamarans.com/index.p...os-talk-at-wbf

    All small boats should have sufficient buoyancy not just to stop the boat sinking, but to float approximately level and support the weight of the crew. That is a legal requirement for small boats in Europe, so makes sense elsewhere as well

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
    good link, thank you

  20. #20
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    Default Re: shellback capsize

    I didn't build in the optional flotation in my Whilly Boat, and I wish I had. I liked the traditional look, and I thought it would be too complicated and add too much time to an already slow build.

    I did a capsize test (my first) and it was very sobering. I did have two large fenders lashed under a thwart, but it was nowhere near enough. The boat was very unstable. Ever tried to sit upright on a boogie board? It was like that. I began bailing with my bucket, but one rail or the other kept going under. Eventually, by really concentrating on balance and careful movement, I was able to get enough water out to row to the dock.

    This was on a calm day right near the dock. In rough or even moderate conditions, I could not have self-rescued.

    I would do what Zuri did above and even make the middle thwart a box full of foam. Why not?

    Good luck!

    Mike
    "near it, a small whale-boat, painted red and blue, the delight of the king's old age."

  21. #21
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    Default Re: shellback capsize

    Quote Originally Posted by dposner View Post
    The boy will of course be wearing a life preserver, but still if the boat flips and fills with water I'm wondering if it will stay afloat, at least enough to sit in it with water up to the rales, and not go down.
    david
    The picture I posted was of my co-instructor at the WoodenBoat School. We were teaching a racing class, using a pile of borrowed Shellback dinghies - none of which had any added floatation. We decided it would be prudent to see what would happen to them in a capsize. Young Milo manned up and volunteered to be the guinea pig in the cold water there. Technically, the pic is not of him trying to hold the boat down, but rather what happened to the swamped boat when he put his weight on it. To be fair, it did not sink any further than this and he was at least able to use it to keep his head and shoulders out of the water (some of the time).

    Alone, a stock, swamped Shellback does not float very high at all, and obviously will not provide significant floatation to anyone in the water. We concluded that self rescue was not happening, except by the most experienced (and perhaps fittest) users, and even then it would be unlikely in lively conditions. We planned accordingly.

    They are fun boats to sail, however.

    Kudos to Richard Woods, btw - he has a done a lot to promote self rescue among sailors of home built boats - including hands on demos in darn cold water.
    Last edited by DGentry; 10-29-2017 at 07:58 PM.

  22. #22
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    Default Re: shellback capsize

    Swim alongside the dingy and rock it back and forth vigorously. Lotsa water may splash out.
    Small side decks kill this trick.
    Practice, of course.

  23. #23
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    Default Re: shellback capsize

    Quote Originally Posted by wizbang 13 View Post
    Swim alongside the dingy and rock it back and forth vigorously. Lotsa water may splash out.
    Small side decks kill this trick.
    Practice, of course.
    Like this?

  24. #24
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    Default Re: shellback capsize

    Yup.
    I used to see West Indian kids do it to their two bow boats.
    Boats with a transom can be done from astern.

  25. #25

    Default Re: shellback capsize

    I see that my videos didn't open directly in my report. Thank you YouTube for changing your website settings!!! But if you click on the individual videos they will open. And you'll see I included the PT dinghy capsize which shows Russell scooping water out when in the water alongside and a girl bailing out a canoe by rocking it. I also tried to explain that just adding more buoyancy isn't enough. You have to place it carefully so that it keeps the boat afloat and also makes re righting easy

    Here is another report on capsize demos I did at an earlier sailing meeting http://www.jimsboats.com/1apr16.htm

    Thank you DGentry and tink

    Richard Woods of Woods Designs

    www.sailingcatamarans.com

  26. #26
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    Default Re: shellback capsize

    Quote Originally Posted by stromborg View Post
    Adding positive buoyancy strikes me as a relatively modern addition. I would have to guess that in the past there was a bit less worry about ultimate safety (possibly because the designer stood less of a chance of getting taken to court by the relatives of some hapless sailor) and because being made of wood most un-ballasted boats wouldn't head straight for the bottom when swamped.
    In the research I've done into the history of dinghy design I've been horrified by the death toll in the days before positive buoyancy. Over 60 people a year were dying in catboats in the 1800s in the USA. The worst tragedies in centreboarders without buoyancy were the loss of about 27 people (mainly women and children) in a centreboard cabin sloop in 1887; the loss of about 15 in a racing fishing boat in Melbourne, Australia; nine lives in an 18 footer in Brisbane, Australia; and at least a couple of incidents in which five people died. There were many others just about as lethal. And they didn't die easily; some of them clung to upturned hulls for days before dying insane; others left their fingermarks in the planking to show where they had clung to the hulls. The death toll was one of the reasons the "length and sail area" rule was brought in, and why governments looked at regulating hire boats in Australia and other boats started to fit buoyancy in the late 1800s.

    The guys who were arguably the architects of the dinghy boom, like Crosby and Holt, both created boats that were specifically intended to have lots of buoyancy and to be safe, because they knew that sailing's popularity rested on safety. It's arguable that the improved safety record brought by buoyancy tanks has allowed people to forget how dangerous dinghies without them can be.

  27. #27
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    Default Re: shellback capsize

    Travis - I like the looks of those float bags in post # 14 . . . thinking they might be a good fit for under the seats of my new Lightning. Could you tell me what brand they are and where I might find them?

    Thanks,

    Mike

  28. #28
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    Default Re: shellback capsize

    They are beach roller bags from Duckworksbbs.com

    Travis.

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    Default Re: shellback capsize

    How about adding something like an Andersen Bailer mounted on the side of the boat, near the load waterline, so that in combination with flotation on the bottom/sides of the bottom, the boat can do some bailing by itself? -- Wade

  30. #30
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    Default Re: shellback capsize

    Good stuff, Richard.

    We just had the Fall Shop Talk & Messabout here sponsored by Chase SMall Craft and the Downeast TSCA chapter. Christophe Matson discussed his experience in a real capsize (turtle!) situation in Casco Bay. Then we went and practiced. It was a great day.
    Clinton B. Chase
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  31. #31
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    Default Re: shellback capsize

    Quote Originally Posted by wtarzia View Post
    How about adding something like an Andersen Bailer mounted on the side of the boat, near the load waterline, so that in combination with flotation on the bottom/sides of the bottom, the boat can do some bailing by itself? -- Wade
    why the side not the bottom? I doubt that the flooded boat would get enough speed when swamped to make the bailer work. Transom flaps may be useful.

  32. #32
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    Default Re: shellback capsize

    On Lightnings we typically have Andersen Bailers to take out the little bit of water we get from spray or leaks on a wooden boat. They are usually in the low part of the hull beside the centerboard trunk. But it is the transom flaps that make it possible for a Lightning to be self-rescuing, in combo with a lot of floatation built into the floor.

  33. #33
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    Default Re: shellback capsize

    Mike, does a swamped Lightning lie on its side, or does it turtle? When I was a kid I capsized a 14ft sloop with lots of flotation molded into it and it turtled and stuck its mast in the bottom. I had to go underneath and retrieve the main halyard and swim it to a couple friends alongside in a motorboat in order to pull the boat right side up.

  34. #34
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    Default Re: shellback capsize

    Quote Originally Posted by tink View Post
    why the side not the bottom? I doubt that the flooded boat would get enough speed when swamped to make the bailer work. Transom flaps may be useful.
    --- I am thinking that low flotation would float the boat upward and get the water to drain from the bailer. It probably wouldn't drain it very dry (unless the floor flotation were significant) but enough to vastly reduce bailing. The bailer on the side not bottom so that in the capsize drama, if you forgot to immediately close the bailer, the waterline position might reduce some re-emergence of water until you got things under control.

    Though I have very different issues as an outrigger canoe sailor, I have experienced knock-downs that filled that part of the hull not excluded by my significant watertight compartments (20 gallons in free cockpit, I should think). I righted and sailed on with that load as I bailed because the compartments let me sail with the stern treading water, but I would have benefited by a port near waterline -- or a hull bottom Andersen of course -- to let the compartments do some of the work. I prefer the waterline port only because it is some protection against failure or forgetfullness. You would be right in thinking I hate the idea of even an engineered hole in the bottom.

    My outrigger-under-construction has a foam bottom under the 15-inch deep plywood topsides, but the foam should float the hull with me in it all by itself, with extra help from fore/aft watertight compartments. I will install a Beckson port or Andersen bailer low on the topsides (aft, and outrigger side) -- the foam bottom precludes a bottom-mounded Andersen of course -- to rid the 24"x7 foot cockpit of water fairly easily (well, the 4 inch diameter Beckson port would); not just from a knockdown, but from spray and waves over the bow, a frequent problem in my choppy local water. -- Wade

  35. #35
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    Default Re: shellback capsize

    Rob - Usually a capsized modern Lightning will lie on its side and is easy to bring back upright. But they will also sometimes turtle. I don't know what the percentage is, but would guess that they lie on their side 90 percent of the time.

    The Class requires boats to have a preventer to keep the centerboard from going back inside the hull in the event of a capsize. It is usually a line attached to the front of the board and cleated to the side of the trunk.

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