Love to have a small sail on the boat

Discussion in 'Boat Design' started by BertKu, Aug 1, 2015.

  1. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Well, it took a little longer then I thought to make a solar powered boat, but here is the end result. I haven't tested it yet in the bay, I first have to get all the necessary paper work etc., but I am happy with the result at the local lake. The thread from Jon E from Norway (Small electric outboard: endurance – real world experience) has given me the confidence that in reasonable current and waves, the boat will move, at for me, an acceptable speed. I haven’t made notes of the various power or distance etc. Will do that one day. 1 of the reasons why it took so long was, I have designed and made my own controller, placed sensors in the 130KV ( per Volt 130 rpm) brushless motors thanks to the help and advice from Jeremy Harris, made my own pc boards, made every bracket myself, made many items over and over again, made mistakes I had to correct, wrote the software, fixed the hull up, etc. etc.
    However, I have a question. I have some idea’s myself, but like to see what others have for a better solution. Par, Ad-Hoc, Portacruise, Daiquiri. I like to have a small emergency sail mounted with a small mast on this cabin cruiser boat. I will have to calculate the various parameters. But what kind of sail and what should the maximum size be? Something, what does not endanger my life and crew, but what will help, when there is a little wind and for whatever reason, the motor is no longer working, although I have a back up.
    Any suggestions and if possible a small sketch? Bert
     

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  2. Manie B
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    Manie B Senior Member

    Bert please post a video of her on the water, love to see it moving along.

    Regarding a small sail, it's do-able but you will need a rudder and some kind of a leeboard. Upwind sailing and crosswind sailing will just not happen - but going downwind thru about 30deg to the left and 30deg to the right is reasonable to expect. I would much rather suggest a small 3hp 2stroke outboard far far better.

    Anyway very interesting project.
     
  3. BertKu
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    BertKu Senior Member

    Hi Manie, thanks for your reply. The problem is , I am on my own and I will find one day somebody who can come with me. Also, I am in the process of getting a new mobile phone and hope to get a couple of apps for this phone for sailing/boating. My rudder is hopeful large enough, as my motor compartment function as rudder as well. I am fully aware that with a sail it will perform quite a drag. I have a spare brushless motor system, not fond of petrol engines, spare battery power, but am intrigued to have a sail, which I must be able to manage from the steering wheel. Manie, could you give me a sketch what you had in mind? Thanks. Bert
     
  4. Manie B
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    Manie B Senior Member

    Bert I would go for extreme simplicity because the sail is not intended for serious work and is basically just a downwind extra. It will be fun on the days that the wind is blowing softly in the right direction just to float along.

    Roller furling headsail. Keep the mast very short and I would put it there where the guy is standing in your first pic. It could be a fun project but like I said nothing serious. You don't have a keel or ballast so never open the sail up big because it will flip the boat.

    There are obviously problems with this kind of experimentation but fortunately you are technically minded so you'll be able to work around the problems, it's just my 2 cents :)
     

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  5. BertKu
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    BertKu Senior Member

    Yes, I thought something in the same way, with the exception to kick out the heavy 84 Kg batteries and replace them with Lithium of only 24 kg. For the 70 kg, I could have 2 folding up pontoons and make the boat a trimaran from it. Flipping over would then not so easy. I can in anyway only go onto the sea with good weather. I rely on ww.yr.no (Norwegian site) to give me as usual an very accurate weather picture. As an unique way of cooling, I have the brushless motor running in transformer oil. The transformer oil will be cooled by the sea/river water. Bert
     
  6. Petros
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    Petros Senior Member

    consider a simple junk rig. It is very easy to single hand, it has low stress in the rig so it can be light, it is efficient and easy to reef if the wind picks up. and it will not flog, and much less likely to capsize you if you keep the size small.

    However, throwing in an extra and inexpensive trolling motor as your back up might cost and weigh less than an undersized, sailing rig would cost.

    Good luck.
     
  7. BertKu
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    BertKu Senior Member

    Thank you Petros, I will consider your proposal and see what I need to do. Thanks. Bert
     
  8. CDK
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    CDK retired engineer

    If going downwind is all you want, try a small parachute made from water repellant fabric. With your electric drive as a rudder you could probably even steer a bit and recharge the batteries.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    parachute or kite sounds more likely, but the arc would be pretty limited.
     
  10. PAR
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    PAR Yacht Designer/Builder

    Considering the shape of the bearing area on that hul, you'll want a low aspect rig, maybe square or quadrilateral shape. A lanteen might do too. It'll have to be an off wind rig, without a centrally located appendage, though tossing a leeboard over the side could help a bit, maybe getting you as high up as a close reach.
     
  11. BertKu
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    BertKu Senior Member

    Hi CDK, Yes, I also thought about that one, but it will be very difficult to handle it on my own. My wife had a fall from her horse 6 years ago and she still have hip problems. A kite or parachute is not easy to handle for me on my own. I will make a sketch of what I had in mind. Bert
     
  12. BertKu
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    BertKu Senior Member

    Thanks PAR, I mentioned to CDK that I will make a sketch in what I had in mind. That would be easier for you then to give me some valuable advice.
    Bert
     
  13. BertKu
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    Location: South Africa Little Brak River

    BertKu Senior Member

    CDK, Remember your comment on my "Toilet seat", I must say it did not work out too badly, although I did moved away from a "toilet seat". Bert
    P.S. If I had made a toilet seat type of construction, it would have been a disaster. Thanks for pointing it out.
     

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  14. BertKu
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    BertKu Senior Member

    PAR, CDK, Manie, Mr Efficency, Petros, this is what I had in mind. Do you think is it too dangerous and I need to place 2 folding up pontoons at both side? I thought to extend the bow with a strong stainless steel piece of metal and an aluminium frame to hold the folding up mast. With 2 ropes from the sail to the cabin. This way I am able to reef the sail in or out from the steering wheel , on my own. If necessary, I maybe have to mount 2 swords boards on both side of the hull, like the old Ijsselmeer fisher's boats have. Bert
     

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  15. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Do you mean something like this,

    https://sp.yimg.com/ib/th?id=JN.tTATCBYu+UmMPnXvhkdv8A&pid=15.1

    Certainly a possibility. I am struggling in how to reef the sail quickly down or up. Down would be better without too many ropes. I am however worried that if the wind turns suddenly, I may flip the boat. How can I avoid that?

    Thank you. I bought in total 5 brushless motors. Two of them, I destroyed in the process of placing sensors in the motor and am in the process in making an inexpensive type of trolling system from one of them. The software runs very smoothly, according to Rick Willoughby much less noise that a normal ESC controller. Also I can run the motor at 1/2 rpm, which cannot be done by an ESC which is based on back EMF. Bert
     
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