Foremast rake and sheeting angle

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  • 09 Nov 2014 18:07
    Reply # 3146312 on 3143435

    There are definitely advantages as well as complications with three masts. For me is was a relatively quick and easy way to avoid  extending the main mast to its original 10.5 meters and maintain original sail area. I also liked the increased options and the tiller balance. The lower aspect meant less reefing the main, and little sails were easy to make and easy to manage. The smaller main had a powerful sheeting ratio, so easy to trim without a winch. The reason I am extending the main mast again is to get better performance in lighter winds.

    My original fore mast was only 5 metres long to begin with and was light enough to be man handled. Both foresail and mizzen took seconds to hoist. It was very little work for a significant difference in performance and handling. The extension added both length and weight and to answer the structural question...yes! I never got the sheeting right with the 18 degree rake and on occasion it didn't reef properly either. I was pressed for time and too keen to get up to the Bay of Islands in time for the meet. Take plenty of time to test hoisting and dropping when on the mooring.

    The original 8 degree rake, 5 meter mast worked surprisingly well. It is strong. The taper was 120mm at the partners and  60mm at the mast head. Screw/ glued and glassed over. The sail was only 6 square metres.

    Even with the extension, I didn't notice any excessive movement or fishtailing on the mooring. Shoestring is high sided and comparatively light for a 10 metre yacht, and where I am moored, it is  exposed to a strong sou-wester with wind against tide. Nonetheless, my anchor dragged a couple of times on the trip. Having said that, with enough chain out  in a blow, it dug in VERY well. Windage aloft could change your judgment on how much chain to put out.

    I don't know about the 'hoist' idea although I am sure it has been done before. Maybe others will know.


    Last modified: 09 Nov 2014 18:46 | Anonymous member
  • 09 Nov 2014 14:23
    Reply # 3146217 on 3143435
    Deleted user

    Thanks for the reply, this is very useful information for me, I'm on my way back to the boat tomorrow and the first job wil be setting up the new masts. 

    I gather that the problems with exceeding 15% forward rake were structural, and not with reefing or sheeting? I am also setting up a 3 masted rig and your success with wing wang wong appeals very strongly. Sounds like a wonderful way to sail.

    My foremast will be stepped in a steel tabernacle and if 18 degrees turns out to be too much, it will not be difficult to alter the angle, a few days work at most. Reducing the angle would be easy but increasing it would be somewhat more difficult, so I'm thinking I should try it first at around 18 and see how it works.

    Another benefit of an overhanging foremast is that I plan to use it as a man overboard rescue device, my old method was a lifting tackle from the starboard spreader, which of course is history now. My boat is high sided and a way of hoisting a person out of the water is rather important, or at least it could be some day.

    One more thing: I'm not sure how a 7.6 m mast set far forward will affect how the boat will lay to anchor. I've read that the Chinese used to stow their foremasts when anchored, do you think this will be a problem?

    Last modified: 09 Nov 2014 14:32 | Deleted user
  • 09 Nov 2014 01:28
    Reply # 3146126 on 3143435

    Hello Robert,

    Every boat is different and you will probably have to play around with it. I started with 7 degrees and when I extended it, it was about 18 degrees. That was too much. I think somewhere between 10 and 15 degrees is where it should be. If I do it again, I'll go with 10.

    The foremast and rig was rush job. I was originally intending to put in a self tacking jib but junk sails are a lot easier to make and reef. Shoestring is built very strongly so there was absolutely no problem placing the mast right at the bow and stepping  it into the anchor well.  I did however set 2 plates of 20mm marine ply under the foremast. I was conscious of the more extreme  movement at the bow and sandwiched a piece karrimat (camping foam bedding) between the two pieces of ply as a kind of shock absorber. I used very long hardwood wedges cut out of an old school seat that was going to scrap.

    The problem was that I built the mast in a hurry and it was about 500mm too short. I had to keep the lower panel reefed all the time. So I made a rush extension before the summer set in, and raked it forward thinking it would help with tacking.

    The little bit of extra sail area helped and I sensed that raking it forward made the tiller lighter. It could almost self steer. In fact I was doing what Brian Platt did and set the mizzen and mainsail to spill a slight amount of wind and the foresail brought the bow back to lee. It self steered long enough to make lunch on the way south from the Bay of Islands. Further south the wind changed and self steering seemed to work better on a reach or close reach.

    Generally it performed well with the 18 degree rake, but between squally weather, williwaws, and beefy southerlies, the extension eventually gave out. It was in some ways predictable. I was able to salvage it  and reinstate the original shorter mast for the home trip to Auckland and since then I have removed both mizzen and fore mast and intend to lengthen the main mast this summer.

    I am still not adverse to a foresail, but a lot depends where your main is positioned. They work well and look quite well when the sail is up. It looks strange anchored along side other cruisers, but still got compliments.

    Hope that helps.


    Roger


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  • 08 Nov 2014 21:30
    Reply # 3146026 on 3143435
    Deleted user

    My foresail will look pretty much exactly like Shoestrings. I see in your profile that you increased the forward rake, what would you say it is in degrees? Wondering how much rake I could safely give it.

  • 06 Nov 2014 19:07
    Reply # 3144132 on 3143435
  • 06 Nov 2014 18:45
    Reply # 3144114 on 3143435

    Hello Ben,

    Sorry I didn't reply sooner. Am a bit preoccupied with my main mast at the moment.

    I build a little foresail for my current low aspect rig. When sailing, I found that the rake did not affect my sheeting, but my main mast is set far enough aft to allow for that. Furthermore, my sail shape is slightly different to the drawing you have posted. I will upload a photo.

    I only had one 3 point sheet span coming off the boom and next two battens. The luff seemed to tighten quite well and form shape when on the wind. The sheeting occasionally caught on the bollard forward of the main mast, but that is easily fixed. A bigger sail would have required double sheeting as Graham has explained.

    I found the steep rake rig self-gybed before any of the other sails even came close, so it was a great indicator and wonderful for wing wong, or in my three masted case, wing, wang wong. It was totally automatic. With the steep rake however, I had to be careful not to allow it to swing too far forward. In my second blustery gybe attempt, just off Waiheke Island before the 2013 junket,  it somehow wrapped itself around the mast a couple of times and refused to reef. I had to motor the opposite direction to unwrap it. This was not caught on camera am happy to say!

    Roger

    Last modified: 06 Nov 2014 18:46 | Anonymous member
  • 06 Nov 2014 07:23
    Reply # 3143647 on 3143435

    If you have a sail of this shape you will need to use double sheets as there will not be enough room between the masts for single sheets (note how far aft on the drawing the sheets drift.  I think a fanned sail like this does give a nice shape, assuming it is a flat-cut sail and not built with cambered panels.  If your foresail has cambered panels it will not need to be fan-shaped like this.  If you prefer flat-cut sails, (and I'd understand that, despite having a cambered sail myself that is very powerful) you can compromise on the profile of the fanned sails along the lines of mehitibel.

  • 05 Nov 2014 22:49
    Message # 3143435
    Deleted user

    I would like to hear the advantages and disadvantages of a foresail of this design. I am leaning (pun intended) towards a smaller foresail of this design, with a larger mainsail. Does the forward mast rake and decreasing batten length make for more clearance for sheeting or more sheeting problems?


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