I think he was referring to the poster who said they only come in one length.
i have an old windsurfer mast on my outrigger canoe. The sail is a sunfish sail. It is terrible when the wind is more than about 10 mph. All the draft in the middle of the sail disappears.
Hobie makes a carbon mast for the island trimarans. I imagine it has better stiffness than a windsurfing mast. Not real cheap but probably much cheaper than custom.
If you choose the Mellonseed ,then you can compensate for the weight of the rig aloft by just shifting your position a few inches off the centerline ; no carbon fibre required .
Thanks for pointing out posts #21 and 24. Yes, that IS nonsense. Windsurfer masts are NOT standardised with regards to coming at a single length (4.7 mtrs) only.
The poster of No. 24 refers to the windsurfer mast being bent by the curve of the sail luff-pocket in connection with the sail foot outhaul. Windsurfer masts themselves do not come pre-bent, they come straight as an arrow.
And to all who think that all windsurfer masts are too bendy: Some (those with a low IMCS value) are intentionally bendy, some (with a high IMCS value) are intentionally stiff. Buyers can pick their preferred stiffness over a fairly wide spectrum.
Using windsurfer masts can save a lot of money. They offer an excellent price / performance ratio, but there surely are better systems on the market, at a price.
Being one who has a bit of experience creating and adjusting sail shape there is no way I can agree with that statement - and if you are going to be measuring bend and its relationship to sail shape, you need to learn the proper way to do it. Even when done properly it is a very crude estimate at best, but sometimes better than nothing.Using windsurfer masts can save a lot of money. They offer an excellent price / performance ratio
For those who want to understand mast pre-bend, see if you can hunt up a description of the soda straw principle. These things are out there for those who bother to look for them.
Thanks for the discussion about windsurfer masts, but I won't be going that direction.
Carbon masts are light and strong but also shatter easily if banged against anything. I've seen sailboard masts rendered unusable from being being dropped on the road from only head height.
There are a lot of sailboard rigs around, ranging from simple, lightly stressed rigs through to complex, highly stressed rigs. Using one of these for a canoe or other small craft could be a very economical way to go, with a bit of imagination. They're available second-hand for very little money.
Last edited by RFNK; 04-18-2017 at 04:21 PM.
How about a hybrid mast, say a lighter-than-normal birdsmouth with a braided sleeve of glass or Kevlar over it? I have no idea how one would arrive at the proper dimensions, but it would be home buildable, light, and strong.
21 and 24 are Todd Bradshaw and Steve Clark, one a guy who has spent most of his life making sails, has written a tome on sails and has sold high performance boats. Steve was the biggest dinghy manufacturer in the US. The A class catamaran champion, invented the modern canted keel, and has the first foiling boat designed for the masses.
I'd hesitate before describing their views as "nonsense".
It it disheartening at times, to attempt a discussion about technical matters. Too many people who don't read the whole thread before commenting... which leads to confusion and unnecessary repetition. Too many people willing to speak with certitude about things they only half understand. Thanks to those who speak with knowledge and accuracy. And thanks to those who shared sources. If I should ever need a carbon-fiber spar, I imagine I'll speak to them on technical questions. I imagine it's only a matter of time. The technical knowledge is spreading, and costs are coming down. And the weight savings are remarkable.
"It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)
Interesting note about windsurfing masts and sails, the ones I used in the mid to late '90s when I was really into windsurfing; you rigged the sail with close to a quarter ton of downhaul and zero to negative outhaul. Sitting on the beach, the sail looked terrible, with a floppy wrinkled leech, but under load, the sail would shape up really nice.
I did jamb about 6 feet I cut out of a broken mast into the bottom end of the the one I used on my outrigger canoe, then filled the inside with 2lb pour-foam in a vain effort to stiffen it up. It didn't work too well, and despite having an adjustable outhaul to work on the sail shape, it's pretty much the only part of my boat that I'm not really happy with.
Last edited by trent hink; 04-18-2017 at 06:58 PM.
Just a note.
I have contacted Ben Fuller about an unused mast.
He said the original cost was around $1K.
Axel Schmidt (canoe sailor) builds masts in Europe, so he referred me to Ron Shell here in the US. Haven't heard back yet.
Haven't received my plans yet, to see the requirements.
Thanks for all the comments.
Being occasionally wrong on a technical fact shouldn't merit a nasty comment, IMHO. Just the facts as you know them. It's easy enough to check if there are some references given (not often the case).
Last edited by David G; 04-18-2017 at 09:57 PM.
"It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)
I also personally wish we could get more specific information with references to companies/ articles/ etc. - some kind of justification for what is presented.
Also being specific about personal experience could stop bickering.
Just to complete this about carbon windsurfer masts, while we're here:
On the boat below are 4 different windsurfer masts being used as spars and masts. The photo is also a study about the actual bend that can be expected under real race conditions. The boat depicted was sailing close hauled in the Venice Raid (Italy) at the time, and the wind was 4-5. Some minor creases in the mainsail, but otherwise good sails profile.
That boat made second overall in the Sail & Oar class.
From an epoxyworks article...
"Hugh Horton felt strongly that we needed a three-piece mast where we could leave out a center section so it could be reduced from 12′ to 8′ in length, such as happens with the gunter reefed mast. The problem with joints is that no matter how well done, they increase weight and degrade stiffness and strength potential. Enter Paul Beiker, boat designer and engineer, with extensive experience with the use of carbon fiber in masts, poles, and booms for International 14 dinghies. We gave him the challenge of developing a three-piece mast that would meet our needs (Figure 3). Within a month, he delivered parts for the perfect mast, plenty stiff, strong and weighing only 4.5 lb (2.8 lb when reefed)."
Might be also worth speaking to Paul Beiker, Seattle if you want to buy a Bufflehead mast in North America.
Last edited by Edward Pearson; 04-19-2017 at 05:07 AM.
I don't see any nasty comments. But an error is an error. Even if Stephen Hawking said that windsurfer masts were all standardised to a set length, it would still be wrong. Is it wrong to point that out? Go to any site you like where masts are sold and you'll see the variety in stiffness and length. And it is simply incorrect to suggest that pre-bend is created in a windsurfer mast with outhaul. This is just not the way sailboard rigs work. Outhaul is used to vary the depth of the foil - that's about it. As noted above, downhaul is the key factor. You want a reference? I've been sailboarding with carbon masts for about the last umm nearly thirty years. I don't know any written references on that subject.
I'm also not suggesting that windsurfer masts would make great spars for canoes. I have no clue about what would make a good canoe mast. But I have seen quite a few people use sailboard masts for rigs on small boats of various kinds, surprisingly successfully so. I looked into this thread out of interest and found, yes, nonsense regarding windsurfer masts. Perhaps I should have ignored it.
If a tree falls in the forest and nobody sees it, it actually did happen.
Stiffness of the mast is measured in IMCS (international mast check system). Longer masts will have a higher IMCS number (i.e. they are proportionally stiffer), which makes sense since they are used on larger sail areas. Masts of the same length coming from different makers will, more or less, have the same IMCS number. Average numbers are as follows:
340 cm - 13 IMCS
370 cm - 16 IMCS
400 cm - 19 IMCS
430 cm - 21 IMCS
460 cm - 25 IMCS
490 cm - 29 IMCS
520 cm - 32 IMCS
550 cm - 35 IMCS
There are differences in flexibility of the tip (more flex for wave sailing sails and stiffer for racing sails). Most are "constant curve" which means that the mast will follow a constant bending pattern (top obviously bending progressively more since it is far smaller in diameter than the bottom).
The carbon content determines how a mast deal with the stresses but not the stiffness itself; a higher carbon content just means that you need less materials for a given stiffness (i.e. a lighter mast still having the same stiffness). Longer masts will almost always have a higher carbon content simply because otherwise they would become to heavy for decent use.
Mast bend is, as others already stated, induced by the shape of the luff sock as well as downhaul tension.
If going to construct a mast for a sailboat out of the windsurf mast, it may make sense buying the longest length possible and cut the top off to get the stiffest part out of the section (the bottom part is relatively much stiffer). The type of rig (bermudan or balanced lug) is a big difference that may be the determining factor in success. I do know that for mizzen masts having a small sail area (up to 3-4m2) maybe, windsurfer masts have been used successfully as well as making yards and booms on smaller rigs.
Some real world experience here. We had a carbon mast made for our BayCruiser 20 by Innovative Composite Engineering (ICE) in WA, who were great to work with. The tube was made on one of their existing mandrels, un-tapered, and in two pieces with a sleeve splice. Size is about 3" diameter, 22ft length, and modest wall thickness because the rig is stayed with fractional shrouds and forestay in Dyneema. The price was around $1800.
The performance of the spar has been great, and the bare tubes were ridiculously light. We added an excessively heavy-duty sail track, wiring, etc. so the all-up weight climbed quite a bit but it is still feasible to just heave the mast into place by yourself.
Unfortunately we got a bit too clever with a mast-raising system led to the halyard winch, and in the testing phases some fasteners pulled out of the wood block at the base of the mast and we dropped the thing on deck. Carbon is obviously very brittle and the mast cracked right in two. Fortunately it was a clean break and ICE was able to make us up another simple sleeve splice for $100 or so and the mast was as solid as ever.
We also use a windsurfer mast for the unstayed mizzen. As others have said, they are very flexy and not great for sail shape, but this is mostly a steering sail and is only about 25 ft^2. It is a bit unnerving watching it pump around with such a tiny sail running jib and mizzen in a strong breeze, but it is not very high carbon content so is quite flexible and resilient.
upchurchmr, you might look into a Hobie Adventure Island mast 65 sq ft 2 part, Austin Kayak and canoe might give you a cost on it ( I couldn't find it ).
Pt # is 79510011.
I too must admit that I misspoke about standardization of sailboard mast lengths.
Beyond that, the point I was trying to make was that a sailboard mast is a perfectly good place to start building the best mast for your small boat. Replace the birds mouth wood spar with something tapered and round and add carbon fiber until it is stiff enough.
In order to meet our price objectives for the UFO ( https://www.facebook.com/fulcrumspeedworks/) we had to make the low cost sailboard mast work as a free standing rig. I have built quite a few carbon fiber masts and know Ted Van Dusen and Tony DiLima well, and knew that they couldn't get within an order of magnitude of what can be bought out of China, but also knew that the 40% standard taper sailboard mast was no where near stiff enough.We did not want to have shrouds, because it is the nature of hydrofoils to stop suddenly, and having stays for the sailors to hit was something we really wanted to avoid. Also the practical value of having a sail which can feather almost through 360 degrees makes handling the rigged boat ashore much easier
We solved this two ways, first we socket-ed the bottom of the sailboard mast into a 2.5 inch carbon fiber tube. that extended about 30" above the partners. This conquered the deck level bending that dooms most sailboard mast conversions at the outset. Second we devised an original jumper strut wish boom arrangement which dealt with the global stiffness of the rest of the spar. We experimented with the variables and arrived at something that was practical, clean and user friendly. Finally it kept the bill of materials cheap enough to hit our $7600 retail price point and still look like it belonged in the same parking lot with the competitors products.
If you look at the photos on the Facebook page, you can see that the sail sets very well and even though there is a whole lot of mast bend, it is matched by a whole lot of luff round. This is not without its consequences. It is necessary to have the jumpers on a tackle which can be released during hoisting, so the sail can more easily get up the mast. The jumper tension is something that can be adjusted along with the out-haul and down-haul to flatten or power up the rig for the conditions of the moment. For this project , which admittedly is a fast and lightly loaded boat, there is adequate tuning range. I need to test it on more conventional boats to really prove my point.
The aesthetics of this project are antithetical to what I believe is the common opinion on the Woodenboat forum, but I think the clever mast and wish boom is a useful addition to the art. We have sought intellectual property protection for this innovation, but have very reasonable licensing fees.
If the carbon advantage is to be used one needs a mast calculated for the individual boat. A canoe mast could be 2kg but you can not put that mast successfully on a wider dinghy. And puting a heavyer dinghy mast on a canoe means you could have used Aluminium instead.
Makenmend - Thanks for that suggestion. I hadn't wanted a Hobie style sail, and therefore didn't think about the mast.
Steve Clark - Thanks also for the design and development description of the UFO mast system. That rig did strike me as pretty innovative. It looks like the sail runs in a track. If so that must complicate starting with a windsurfer mast.
Thanks to everyone about the detailed suggestions, this has become quite valuable to me.
Still waiting on the plans.
I did quite a bit of investigation regarding the use of windsurfer masts for spars. My conclusions were:
(1) it is not viable really, without much modification and adding weight to it, to use a windsurfer mast successfully for high stressed rigs (modern fathead sails, lug rigs).
(2) 490cm is the longest mast length commonly used, meaning that it is easy to find one cheaply (I recently bought a new 490cm mast with 50% carbon content here in the Netherlands for just EUR 100 - if you don't mind a mast that is from last season).
(3) a yard (top part of the mast) and a boom (bottom part of the mast) can be made from such a mast providing a lightweight alternative to wood. In these shorter lengths the sections become quite stiff (at least stiff enough for the purpose and some flex is desirable anyway for the yard).
We resorted to using aluminium (commercially available standard sections) on the Michael Storer Viola 14 canoe design for the mast because of the above reasons. It is a bit heavier, but much much cheaper.
Composite Engineering sells very nice poly-carbonate sail track which we bond to the masts with Plexus.
Has worked very well for most of 20 years.
Some flex in a yard is unavoidable and must be planned for in the sail's design. Desirable? Not so much unless it can be very precisely predictable - which is almost always the product of a lot of experimentation over an extended period of time with different amounts of head round, bend allowance, spar diameter and spar tapers. In general though, the best bet for people putting lug rigs together is to make the yard as absolutely stiff as possible, while trying to keep weight aloft within reason. Excess flex leads to pumping with small changes in wind speed or direction, which is never efficient.some flex is desirable anyway for the yard
One of the ways of getting around the need for track on a carbon or other spar where the sail comes off and you don't want to use sailtrack or hoops is toggled diagonal robands. I have done my gaffer iceboat like this and am well pleased. Toggle's out of shaped dowels, robands out of double braid leech line, seized to the toggle on one end and a loop seized on the other. Patter is forth and back or zig zag up the spar.
Ran Tan, Liten Kuhling, Vernon Langille, Josef W., Merry Mouth, Imp, Macavity and a quiver of unamed 'yaks.
"Bound fast is boatless man."
I can read every word you wrote, but I still don't understand.
Could you provide a picture?
He is talking about lacing the sail to the mast like in traditional rigging but instead of using a continuous line using what in fact is a soft shackle, only simpler (fixed eye on one end, stick as a button on the other). They can be connected as hoops to themselfs or diagonally to other soft shackles replicating traditional lacing patterns.
Thank you Mr. Fuller, this is an exceptional ideea. You solved my main concern about using traditional lacing, not beeing able to quickly remove the sail from the mast. Thank you again for such a simple solution, you made my day.
Another alternative to lacing, or to buttoning with loop and toggle, is using male and female velcro strips on the sail luff. The velcro is neater, however, we found the toggles -in our case little plastic balls with a hole through them- can actually be closed and released better and even faster than the velcro strips.
I forgot something: Here was a lot of mention here of the mast bend. That is where the velcro strips come in handy, because one can adjust them in accordance with the experienced -or expected- mast bend, so that they can compensate for some mast bend and thus avoid sail creases. I admit we did not take this too seriously, takes just too much effort and concentration when hoisting the mainsail. But whoever is very serious about sail profile in connection with inevitable spar bend may use the velcro to advantage.
Last edited by Craic; 04-21-2017 at 08:47 AM. Reason: forgot something (P.S.)