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Thread: GIS Yawl

  1. #1
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    Default GIS Yawl

    Here it is, a lug-and-mizzen rigged GIS!

    (Damn, I can't load it...Mik can you?)
    (MIK: Yap!)



    It worked out exactly as anticipated...stepping the mast in a mast partner 'box' (i.e., a 2nd mast step) located immediately forward of the forward bulkhead. Turns out to be 8" fwd of normal position (assuming I figured out the scale correctly on your drawing, Michael...is it indeed 3/8" = 1"). Also, Mik, it'd be interesting to post your sketch. I like the look of a sprit-boomed mizzen raked aft. Mine is ~16 SF...I factored about 50% of this into the combined CE which lines up exactly with the lug-only CE stepped in the usual position, the aft position in my drawing.

    The process was to trace a drawing Mik sent to me, draw in my mizzen, determine the combined CE and note the difference between it and the CE position of lug only. I moved the lug forward to the forward side of the bulkhead and when I refigured the CE location it aligned perfectly with the CE as designed. So, this is a balanced rig. Sailing hard on the wind it may need to luff slightly to keep weather helm down and it shouldn't add much to the effective sail area. I'll have the benefits of the mizzen and the option to step the lug alone in the aft position and go sailing w/o mizzen. I may see about using a carbon windsurfer mast for the mizzen to keep weight way down...when I want to douse the mizzen or de-step it you remove the sprit and roll up the mizzen (one reason I like a round mizzen) and throw a little line with a half-hitch to keep it rolled up. I have not looked at how well it will stow. I think the boomkin would go on the opposite side of the tiller but it looks low as it follows the aft tank top and extends out...too low?

    As for the skeg...I drew that in last minute...I will row Dana's GIS before I decide it is really necessary for my usage. Hopefully it is not but I'd be willing to take the trade off if necessary.

    The cons of this rig: extra construction time/complication, cost, more things to keep track of/break, and it adds some weight to the boat. I'll take them for the worth of a mizzen making this a great sail-and-oar boat.

    Mik, please give me your thoughts. It looks nice doesn't it? The right area? How about my query about the boomkin?..too low if it just follows the tank out? Anyone know anything about windsurfer masts...would make a great mizzen spar, maybe even boomkin if I can find one cheap. I think the boxes for the mast partner/step would be built right off the transom and the bulkhead before the tops are glued down. What about the skeg thought (lesser of a priority).

    Cheers,
    Clint

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  3. #2
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    Cool Clint!

    Like it a lot.

    Usually with balancing mizzens you only use half the mizzen area for the calculation of the revised centres. This is because the mizzen usually doesn't work as hard and the mainsail and also means that you can pull it on a little bit harder to get the helm balance you want.

    A REALLY light mast is essential in this ... so glad Clint is looking at a windsurfer mast.

    I still like the original GIS for simplicity and low cost ... Hoist the sail and GO!

    When Clint wanted the drawing I suggested my own version. I was thinking the main mast might be able to stay in the normal position and just slide the sail a bit further forward.

    I thought 100 to 150mm was achievable. This would allow the boat to be sailed with or without the mizzen.



    The thing I like about Clint's version is NO BATTENS (I was struggling with myself when I drew it up. Being influenced by the lovely mizzens on the Salcombe Yawls (boats I have lusted over for decades). Though I do like the longer mast of mine (if it can be kept light as Clint suggests. The windsurfer mast would not have to be carbon .. standard glass ones are pretty light.

    Look at these sexy mizzens on the Salcombe Yawls ...


    http://www.flickr.com/photos/25587178@N04/

    The problems I faced were adding the mizzen without upsetting the balance too much. The tall mizzen gives the maximum power to hold the nose up into the wind with the minimum sail area.

    Also I thought with the short boom a boomkin might be avoided by having a sheet each side coming through the transom and going to the boom end.

    Don't know if it will work though!

    Best wishes
    Michael Storer

  4. #3
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    Salcombe Yawl video for MIK

    [media]http://www.youtube.com/watch?v=9RvJzzAv_6M&eurl=http://www.syoa.co.uk/videos.htm[/media]

  5. #4
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    Keyhavenpotter,
    Nice video that class is a new one on me and whata dainty little mizzen a pretty boat.

    I must say that fleet is a polite bunch too all going about on to port in unison to give water room, not sure you'd see that down here.

    Cheers
    Mike

  6. #5
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    Saw them in woodenboat about a decade ago ... the do go upwind pretty nice don't they! Though they have the tendancy of shortended heavier boats to drag their transoms at higher speeds downwind.

    But ripper boats ... don't they fly and spin on a dime.

    As Mike says ... I think that if you have sailed on a river most of your life then the sailing starts to look a bit different ... maybe to have clear air to get across adverse tide is the best choice!? Tide is well out at the end ... wonder which way it was going that narrow stretch.

    Or maybe Englishmen are still polite!?

    "No ... I insist ... you tack first old bean"
    "No ... sorry .... after you old chap"

    An Aussie would be shouting "WAAAAAAAAAAAAAAAAAAAATEEEEEEEEEEEEEEEEER!!!!!!!!!!"

    MIK (not being terribly serious)

  7. #6
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    I reckon there is a fair amount of shouting in the background! Especially the ladies!

    The reason for the different "coloured" fleets is that they have now three distinct groups of boats. The older less racy ones, the improved and race setup oldish boats and then the latest designed super fast ones. These latest designs are by top designers such as Ian Howlett no less. Cost - about £40,000 ouch!!

    Talk about racing increasing costs. What started out as a local fisherman's boat which was raced at festivals is now a boat for the super rich. Now, imagine a bit fleet of Goats!
    Brian

  8. #7
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    Default

    Quote Originally Posted by Compass Project View Post
    Here it is, a lug-and-mizzen rigged GIS!

    (Damn, I can't load it...Mik can you?)
    (MIK: Yap!)

    Cheers,
    Clint

    G'day Clint
    can you darken your lines & re-scan ?
    Can't see the picture
    cheers
    AJ

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    Don't worry about it Clint.
    Managed to 'push' the image in my very old & too good to replace iPhoto express
    cheers
    AJ

  10. #9
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    TX AJ, much better. I use 2H pencil for most of my drawing out of habit...doesn't scan great.

    I think the battened, high-aspect mizzen works well on the Salcombe b/c the main has a similar profile, so the two sails reflect each other, kind of look good together. In the mizzen I drew the sail looks like the lug so it seems to go together.

    Mik the scale in those original drawings, can you confirm it was 3/8" = 1'.

    I need some links or general info to get started on finding a windsurfer mast. Anyone used one before as a spar?

    Cheers,
    Clint

  11. #10
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    Hi Clint

    there are many ex-windsurfers, now too old, who still have a garage full of gear they cannot bring themselves to part with. So ask around your mates first.

    Second, eBay is a great place for cheap windsurfing gear. Carbon masts are still a bit dear, glass ones would be free i should think.

    I believe Swallow boats use a windsurfing mast for their mizzens.

    On page three of the "Lug Rig Heaven" thread you can see my Scow. Her mast is just 50mm alloy tube, however both her yard and boom are alloy windsurfing masts. The gaff from the top 3m and the boom from the bottom 3m of a second mast.

    Brian

  12. #11
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    Howdy Clint.

    There was no scale because I can't control the size your computer prints it out at.

    You have to work out the scale by measuring the metre scale at the bottom and dividing the number of millimetres that you measure by the number of millimetres in the original metres.

    (the originals were both 1/30 on my computer - but that does not mean they are 1:30 on yours)

    The advantage of the PDF of course is I can get it to you in a few minutes.

    Hope this helps
    Michael

  13. #12
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    Thanks...I think I got lucky that when I measured the boat with my imperial scale it turned out to be 3/8" = 1' but I'll double check.

    Thanks for the info, Brian.

    I will check out ebay and I think I have some friends.....who are windersurfer dudes.

    Cheers,
    Clint

  14. #13
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    Default Lesson in sails

    Hi all

    As I'm reading this thread it all looks nice but could someone give me a quick lesson in sails please?
    What is the purpose of mizzen? I see BETH also has it (is that correct).
    Thanks

  15. #14
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    Koala, The answer depends on what kind of mizzen it is...the mizzen can be a trimming sail or a driving sail. As a driving sail, the mizzen carries a fair bit of square footage so that it is an important part of the total sail area...the boat needs the mizzen to help power the hull. In these mizzens they are usually bigger sails and common in ketch arrangements. In a ketch rigged small boat, the helmsman is often behind the mizzen mast. In a yawl rigged boat the helmsman is usually forward of the mizzen mast. Traditional sprit rigged boats were often ketch rigged such that they could carry a lot of sail area without having spars that were too long and difficult to stow. It also kept the total center of effort of the sail plan lower than if the same sail area was packed into one big sail. That was better on these typically tender hulls that the fisherman often would row for hours at a time.

    The other mizzen type is used as a trimming sail. In other words, it doesn't drive the boat much at all, it is too small, but it is big enough to be useful in other ways. My mizzen I am putting in my Goat is very much a trimming sail, small maybe 15 SF at most and it will be raked aft a fair amount. On the water, when raising or lowering sail this small mizzen -- when sheeted down tightly -- will keep the boat head-to-wind which makes life a lot easier, safer and more enjoyable. You can turn into the wind to reef, stow gear, make crew shifts, eat lunch, you name it and the boat will bob head-to-wind and make a crazy situation quite calm. I've used the mizzen to help steer the boat...if I am caught in irons you can back the mizzen and the wind will push the stern in the opposite direction. I've seen, but not tried, backing up with a mizzen...I've watched people sail their Caledonia Yawl backwards off the beach and then turn off and sail away. I've seen the mizzen mast used to hold up a tent over the cockpit. So a trimming mizzen is very useful.

    My drawing may change ever so slightly and will post a final drawing at some point...I may scale the mizzen down just a touch and rake it aft so the rake of the transom and mizzen is the same (which will help in construction when it comes time to build the partner/step) and carry the mizzen CE further aft to make it more effective. I forgot to mention, many lobstering boats carry a small sail aft and use it to keep the boat pointed into the wind...they call it a riding sail. Some people in bigger yawls will keep their mizzen up while at anchor to keep the swinging down to a minimum.

    Does that answer your question?

    Clint

  16. #15
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    Clint

    If all you are using a mizzen for is the trimming function of holding the vessel head to wind, wouldn't it be possible to just use a sea anchor (i.e. a canvas cone with the tip cut off at the end of an anchor warp). That looks like much less effort, takes up less space and you will drift to leeward more slowly as well.

    My view is that a sail that doesn't help with sailing is too much effort, but then again different strokes....
    Cheers

    Jeremy
    If it were done when 'tis done, then 'twere well it were done quickly

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