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Thread: mast rake question

  1. #1
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    Default mast rake question

    I'm building a sail kit for my 14' sportspal aluminum canoe - it is a Bermudan rig, approx. 40 square foot sail area, with leeboards and a retractable rudder - the Solway Dory Expedition Bermudan is my model. The mast thwart and step are hand built with ash. The canoe is foam lined, so I'm not gluing the mast step to the floor of the canoe - instead I'm building ash diagonal bracing to the mast thwart and it will be one unit. I will have the opportunity to make the mast step adjustable fore and aft to add rake in the mast. My question is should I? Do you typically have some mast rake in a canoe sail set up? The canoe is fairly wide and is a utility canoe, so I have no aspirations of it being as fast as a purpose built canoe. But I hope it will point reasonably well. I suppose I could install the mast step to have a perfectly vertical mast and experiment with rake as I go, but I thought I'd ask if I should start with rake, and if so, any thoughts on how much? It may affect how I finish the design of the mast step support structure.

    Thanks.

  2. #2
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    One purpose of mast rake is to tune the location of the CE of the sail. If your leeboard(s) are adjustable), this is probably not necessary, as they can compensate. Rearward rake will reduce the space under the boom, which you may not enjoy. And the sail will present maximum leading edge to the wind if the luff is vertical. And that is my normal inclination with a canoe Bermudan.

    Whatever you decide, remember that there is lots of fore-and-aft force on the step. Diagonal braces to the mast thwart can stiffen things up laterally, but something else is needed for the f-and-a direction. Mostly, those forces push the step towards the rear unless you are backwinded.

    No reason you can't experiment, though!

    Bob

    >The canoe is foam lined, so I'm not gluing the mast step to the floor of the canoe - instead I'm building ash diagonal bracing to the mast thwart and it will be one unit. I will have the opportunity to make the mast step adjustable fore and aft to add rake in the mast.

  3. #3
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    Thanks for the quick response. I'll probably install it straight and go from there. I am hoping I'll be okay on the fore and aft forces. The mast thwart and step construction is all 1x4 ash. I'm using a 4"x4" square of it (maybe double thickness) with a hole through it for the mast step, screwed down (for adjustability if I so choose) into another solid 4"x4" square that the mast foot will sit on. I'm using some joinery to increase gluing surface area and will epoxy diagonal 1x4 pieces (the 4" running fore and aft) to the mast foot and the thwart. I'm hoping the 4" dimension of the diagonal will stabilize the foot fore and aft. That will all rest on a 6" x 8" or so block that will hopefully spread the mast foot forces across more of the bottom of the canoe. It has a strong aluminum keel that runs most of the length of the bottom of the boat, so I think I'll be okay. I could add a brace to the front (or back too) of the structure to further connect the thwart and foot if needed. I'm trying to build sturdy, but not overbuild as I am often inclined to do. I have greatly simplified the transom structure to reduce hopefully unnecessary material and weight. I'm just about done with fabrication of all of it and am looking forward to getting the final sanding and fitting done and all of it epoxied together for good.

  4. #4
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    I always put my mast vertical in the boat. The fore and aft forces will be significant so if you are not fastening the foot to the floor you will need to brace it in the fore/aft direction. I have braced the mast back to the leeboard thwart in the past but it does all get a bit over engineered and heavy if you are not careful. Post some photos when you have finished

  5. #5
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    Here are a couple of pictures of something conceptually similar made for Grumman's Class C sail of the mid-1970s:




    This contraption was very light, being made of folded aluminum. The long extension is anchored to the bow 'mast step tab' that was a feature of those canoes for many years. The fore and aft forces on it were quite strong. I class this as a 'semi-floating' mast step, as the step itself is not bonded to the hull, but the extension IS.



    Above is a picture of a 'rigging deck' that I think was initially invented by John Bull of Solway Dory. It is in effect a 'full floating' mast step. This version is sold by Lost in the Woods canoes in Canada. The picture doesn't give all the details. While several folks have made their own, that approach has kind of faded from view....

    Your idea of a flat plate on the bottom, held in compression, IS a possibility, but I think I'd make it much longer in the forward-aft dimension.

    Alternately, you could fasten the step to the strong keel/keelson that lurks under the rubber foam.

    Quote Originally Posted by klb67pgh View Post
    Thanks for the quick response. I'll probably install it straight and go from there. I am hoping I'll be okay on the fore and aft forces. The mast thwart and step construction is all 1x4 ash. I'm using a 4"x4" square of it (maybe double thickness) with a hole through it for the mast step, screwed down (for adjustability if I so choose) into another solid 4"x4" square that the mast foot will sit on. I'm using some joinery to increase gluing surface area and will epoxy diagonal 1x4 pieces (the 4" running fore and aft) to the mast foot and the thwart. I'm hoping the 4" dimension of the diagonal will stabilize the foot fore and aft. That will all rest on a 6" x 8" or so block that will hopefully spread the mast foot forces across more of the bottom of the canoe. It has a strong aluminum keel that runs most of the length of the bottom of the boat, so I think I'll be okay. I could add a brace to the front (or back too) of the structure to further connect the thwart and foot if needed. I'm trying to build sturdy, but not overbuild as I am often inclined to do. I have greatly simplified the transom structure to reduce hopefully unnecessary material and weight. I'm just about done with fabrication of all of it and am looking forward to getting the final sanding and fitting done and all of it epoxied together for good.

  6. #6
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    I like Mr. Cavenagh's idea of going straight to the keel. In my tortured world of modifying aluminum canoes, I see no great harm in drilling a few well thought-out holes in order to fasten a secure and practical mast step permanently to the floor. In a Grumman, the step is held to the flange by four 3/16" bolts and very small nuts. I've pounded the crap out of my rig and it has never come loose. With your Sportspal, having a few round head bolts sticking up through the bottom, secured by nylock nuts inside, will never be noticed underway. Seal under the step with 3-M 4200 or something similar. Drill from the outside to avoid hitting rivets. Make your step from a block of wood of your choosing, coat it with thinned epoxy. For and aft issues no more. Voila!

  7. #7
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    First sail happened today. Rather light winds but made the best of it. It pointed quite well and was plenty stable in those conditions.

    I ended up using 3m 4200 to attach the mast step to the hull - it was needed.

    I have a few questions about fine tuning my set up.

    I'm using a sail for a Sabot - it had the right dimensions, sail area and was new and cheap. The sail uses a sleeved luff like a laser. As is, I can't get it to stay wrapped to reef. The rest of my sail control system works great. I'm considering adding grommets to the luff and an eye to the top of the mast and attaching the sail to the mast that way. Does anyone see a major downside to that? I don't want to ruin the sail. Is the existing reinforced luff enough for the grommets or do you think I need to slide something in the sleeve for more reinforcement at each grommet location. A few pics to show my current rig after its maiden voyage may help out. Don't mind some of the tape and pipe clamps as temporary fittings until I decided where I wanted to mount certain things for good.

    https://goo.gl/photos/BzHLKt18s9kURVa87

    (I can't seem to get the individual pics to show, but here's a link to the album)

    I think the mast as is is about 2-3 inches too long, putting the sail too high. I'm going to leave it for now, as if I add grommets to the sail, I'll need the extra length to attach the head of the sail.

    Last question, does anyone use a halyard, or do you just tie the head of the sail to an eye mounted at the top?
    Last edited by klb67pgh; 25th-June-2016 at 10:20 PM.

  8. #8
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    I know nothing about canoe rigs as you show, but Topper sails have a luff sleave and are attached to a mast head crane, either by a small loop or a halyard.
    The down haul or cunningham, and the kicking strap or vang, both terminated on the mast. the kicking strap fastens to the boom, so always points along the boom, whilst head and cunningham rotate as you roll the sail up, and are prevented from unrolling by the kicker. I have a pair of Topper rigs at home at the moment, but you would find the photos available via Topper International clearer than any I could knock up. Topper sails have no battens, so can be rolled right up if needed.

  9. #9
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    Are you thinking of a traditional reefing system where you lace the main sail to the mast, then employ a down haul to lower it for reefing around the boom? I say a down haul so you can do it from the cockpit area and won't have to crawl fwd and do it by hauling down the sail by hand.

    If so, you won't be ruining the sail, but you will alter it from a Sabot sail to one that incorporates your own mod. Doing so would entail folding the luff sleeve over til the luff is straight - or parallel - with the mast, then stitching it down, making it twice as thick. That will be more than sufficient for supporting a grommet every 12 to 14 inches from the tack up to the head. Dacron self sticking tape comes in 3" wide rolls and can be used for the reef points as well as the upper tack and upper clew corner reinforcements. I have a very powerful setup on my trimaran that uses the same stick-ons, and it is bombproof, even in very stiff breezes. My luff is sleeved, but it is a gunter, so it will remain so. Still, if I opted for a laced main, it would be as easy as yours to accomplish.

    Having said that, if you have a mast that can be rotated to reef, I would first try something that would enable that feature - even consider button snaps to hold the material to the mast in a couple-three spots as you rotate the thing. Then, if it is still not to your liking, go to a laced main. Some of these other guys have sails like that and may be along shortly to help out.

  10. #10
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    Thanks to you both. I had decided that reefing around the mast might not work with a luff sleeve, but clearly it is possible. I forgot about the Topper line - I was thinking of a Topaz Taz sail before I found the Sabot sail cheap.

    I definitely want to reef around the mast. I was trying to rotate the mast to roll it up and the head of the sail kept slipping. I need to keep the Cunningham tight I think and wrap the sail a few times before I start spinning the mast. I do have battens so I won't be able to reef to zero, but it will get close.

    I should add - based on what's shown in the pictures in my link, if anyone has any suggested improvements or changes, I'd be happy to hear them. I race a Sunfish and sail an O'Day Daysailer II, but I'm new to canoe sailing. I borrowed heavily from the Solway Dory Expedition Bermudan, which to me was a very well thought out and executed design.

    If I leave the luff sleeve and figure out how to get that reefed, would you lop a few inches off of the mast height to get the boom and sail lower, based on the pics? I was very comfortable to sail that way, but to my eye is too high.

    Phase II may be outriggers and likely will include a rudder uphaul. I used a Hobie rudder blade and its weight seems like it will keep it down just fine. I have the bolt tight enough now that it will hold itself out of the water, but I have to get back there to push it down and deploy it now. I'll have the canoe on a lake in Ontario Canada for the next 10 day and am looking forward to much more time on the water and hopefully sitting on the gunnel in bigger wind, and tweaking as i can.

  11. #11
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    One question about the mast step: You indicated glueing it down with 3-M 4200, right? That is what I had suggested earlier. However, did you also bolt through the bottom as well? 4200 is a sealant, not specifically an adhesive by itself. For a stand alone I recommend 3-M 5200, or it's market equivalent.

    Now, about the furling mast: Like I said, I don't have one but your issue should be easily resolved. All you need is a way to keep the cloth from slipping out of tension as you roll it up. So why not installed a couple or three grommets along the luff and thread 1/4 inch lines through them. When you setup for sailing, just tie them around the mast to snug up and that should do the trick. Even if they slip initially, they might start gripping as soon as the material begins to go 'round, IMO. Just thinking out loud here... something that might stick to the wall.

  12. #12
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    OutnBacker - 4200 is listed as an "adhesive sealant", and so far I haven't seen any movement in the mast foot, but I'll definitely keep an eye on it. I have rivets that run the length of the keel to attach a reinforced aluminum keel, so I could drill a few of those out and replace with screws (or just make new holes for screws if there's room there). You'll see in my newer post that a bit of line tied around the sail and mast at the top was all it took to get it to reef like it should. A good simple fix.

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