Sailing in weeds

Discussion in 'Boat Design' started by Skeezix, Feb 1, 2022.

  1. Skeezix
    Joined: Feb 2016
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    Location: NE Iowa

    Skeezix Junior Member

    I hope readers might advise me. Sailing monos on our increasingly weedy lake is becoming a hassle, and moving me closer to building a trimaran. Hopefully some readers have had positive experiences. What features, and examples of tris with them, would be best where weeds are frequent?

    Hull shapes: Bow profiles, length, draft, main hull beam? Ama design?

    Rudders: Single or double? Particular designs that are quick and easy to lift clear of the water?

    I suppose water stays are out of consideration?

    Daggerboard/centerboard/leeboard choices?

    Other thoughts?
  2. The Q
    Joined: Feb 2014
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    The Q Senior Member

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  3. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    I'm not sure how changing to a multi-hull will keep you out of the weeds.

    You will still need deep weed catching boards/ rudder.

    Racking the boards after should help weeds slide off. Weed cutters might be useful. Otherwise frequent lifting of the boards will remove snagged weeds.
  4. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    The primary needs of a working sailboat are the sails and some form of lateral resistance that allows easy forward motion. The keel accomplishes this latter aspect of a sailboat. On solid ground, wheels do this, or rails. In something like heavy weeds, where resistance to motion is great, a skid-like keel should work. You won't need the depth of a fin keel, but to continue efficient sailing when out of the weeds, a swing keel and kick-up rudder should work well.

    My instinct is that a scow with leeboards would be best. The flat bottom of a scow would help keep the draft shallow. The next best option might be a catamaran with swing keel. Beamy will help keep her upright. With a kick-up rudder, heeling may not serve you for control. A double rudder would be best to keep control on a reach.
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  5. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    A long-shallow keel with an attached rudder may do the trick.

    The price is of course some windward ability. Deep, short keels are, for their area, windward Champs. But they imply a long, mostly vertical leading edge,which the weeds love to hang onto.

    A long, shallow keel can have a greatly raked leading edge and still work. And the leading edge is a whole lot shorter. If the rudder depth ends above the bottom of the keel, there will be little risk of weeds catching on the rudder.

    But the keel adds draft.

    One way around that is to have a "V" bottom boat and put two long bilge keels on it. Then, you would need a long skeg in front of the rudder.

    It would be interesting and maybe instructive to race a boat such as this against a more conventional design on this weed choked lake.

    A less extreme idea would be to have a center board that has a triangular shape underwater, with a great deal of rake to its leading edge (more than 45 degrees from vertical). The rudder blade can pivot fore and aft, and have some mechanism to pull it down automatically. Then an up-haul line can be added, to pull the blade up, to shed snagged weeds.

    Whether or not this idea could beat my first idea, depends on how bad the weed situation is. If it is utterly terrible, the long keel would win the race, because the other boat would be raising its rudder blade all the time.
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  6. Skeezix
    Joined: Feb 2016
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    Location: NE Iowa

    Skeezix Junior Member

    The Q: Current monos are an O'day 25 with a centerboard within a short keel, and an off-brand 17 with a swing keel. Both with swing rudders.

    The O'day is limited to always sailing board up. Tried it with the board down and it gathered so much weeds around the pendant that it was impossible to sail. And even board up, at worst of times I go into irons to back off a wad of weeds on the keel. Rudder dumps are a common hassle, as it has a rudder that runs deeper than the keel. I am afraid any boat with space below will be a weedplow, but perhaps I might redesign the rudder. It will just be a boat to get out on the water in comfort, with weeds the price to pay.

    The 17 (Silverline Dolphin) has a heavier swing keel that can dump weeds OK and even climb over them if I run it partially retracted. Rudder dumps are a hassle because it does not now have a way to quickly lift the rudder.

    Blueknarr: A tri has triple the waterline to resist windage, especially if it has hard chines. And it has less draft, to skate over weeds, especially if I build high volume amas. While two rudders mean you catch two weed paths, they need not be as deep as a single rudder. And one keeps steering while you dump the other.

    Will: Scow is a good thought. They do well here. Not sure I want to hike out or get wet so often. Leeboards are a good idea: You can see the weeds, they might dump more easily, and no center slot to clog. Frank Smoot puts leeboards on his tris, as much for ease of construction as any other reason, I think. Skid keel is a good idea too, though it makes it harder to come about. I also think any hulls should have a long gentle entry instead of the straight or reverse bows in vogue.
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  7. Skeezix
    Joined: Feb 2016
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    Location: NE Iowa

    Skeezix Junior Member

    Sharpii2: I agree with your assessment, thanks. I think a long shallow profile is the way to go, if I make a tri with all hulls quite narrow. What I lose in pointing ability might be made up in VMG, especially when weed dumping time is a factor.

  8. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    I wonder how fast you are travelling through the weeds, as rudders are not very effective at very low speeds- would be hard to turn around if you're barely moving? My out-of-the-box idea which is probably worth zilch, is to use something like 1 retractable drag chain or with something just buoyant enough that has slight friction dragging on Weeds- on each side-, haha! Then control the steering by the length of each chain that is let out, haha! Of course, that goofy idea wouldn't work very well in non- weedy water, one would have to go to backup retractable rudders for that situation....

    Ps. I'm picturing a thick anchored weed mass and shallowish water. A planer board on each side of the boat that is horizontally hinged with the flat face forward might just give enough drag for Sharp turns at low speed on a cat. The flat side of each board could be independently forced downward into water as needed for varying degrees of immersion, causing a brake effect against the weed and water Mass ( and weeds would slide past, under and around the flat face). Forgive me if this is what was written in the planer/ lee board / swing rudder discussions above.
    Last edited: Feb 3, 2022
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