How to convert a 18ft bare hull w/60HP outboard to JR?

  • 19 Jul 2017 10:46
    Reply # 4984068 on 4976050
    Deleted user

    Thanks Graeme for all the clarifications. Do not worry about me misinterpreting your suggestions, I know that I cant make a race horse out of a donkey. Furthermore, I have three children and with it a strong instinct to keep them safe. I'll keep this thread updated with whatever progress I make. For now, procuring an adequate aluminum pole and learning the ABC of resin+fiberglass are in order. All the best.

    Last modified: 19 Jul 2017 10:52 | Deleted user
  • 19 Jul 2017 10:39
    Reply # 4984055 on 4976050
    Anonymous member (Administrator)

    Hi Dom, when you reply you don't have to hit the "quote" button, just the "reply" will do.

    I am still not sure if we are on quite the same page. I think the hull will carry sail and for a motorboat its not too bad a shape for sailing, and even modest performance can still be quite fun. Having said that, I think that motor is going to limit you to what will be at best a bit of fun and a learning experience, which is good and to be encouraged. I am not qualified to go much beyond that and I did not mean to suggest anything about providing for a real emergency - but I will go a little further now and speculate that once you have tried out a modest little rig of some type, with whatever you have easy access to, and had a bit of fun with it, I honestly don't think you are going to go too much further with sailing it while still maintaining such a big heavy motor on the back. I might be wrong.... I don't mean to be negative and am not criticising the motor either, I think it looks like a really nice motor boat and I bet it goes really well - and what is more looks as if it would run quite nicely and economically with a lot less power too, if you had to, and not all power boats have that virtue. 

    I still think a sailboat on a trailer might be just the thing for the sailing conditions you describe, and for what you have your heart set on doing. Here in NZ some people do that, there are public launching ramps and people just just bring their boat home, or keep it in a sort of boat parking lot, when not sailing. I am  not sure if you have that sort of boat or facilities available in Mauritius.

    Anyway I wish you the joy of being out on the water getting the best of what your handsome little boat can give you. Good luck.

  • 19 Jul 2017 07:35
    Reply # 4983849 on 4983571
    Deleted user
    Graeme Kenyon wrote:

    Dom, just to make it clear, any opinion I might have about JR is of little value because I am in the beginner category with that particular rig, same as you. All I can tell you about that is that you are in the right place to get the best advice, if that’s the rig you want to go with.

    What I meant to say is that with a bit of improvisation you can have some fun learning how to make that very nice motor boat sail, if you want to. You might be still a little distance away just yet from knowing what sort of rig you want – if indeed you even really want to sail - so why not just start with a simple home-made lug sail on a mast you can lift in and out, and a blade you can lash onto the outboard leg.

    Imagine you are lost at sea with a broken-down motor and have to make a jury rig with what is available and at hand. You will be able to make that thing sail alright, that’s for sure. Pick your weather, have some fun and see what you can learn. Its called “messing about in boats….” its all good fun and that might be as far as you decide to go with it.

    That hull shape won’t stop you from being able to sail moderately well, even to windward with a bit more lateral plane, which does not have to be a foil. But just don’t forget that if you have to carry that motor, then quite a big chunk of your total weight is right at the back and up over the waterline which is far from ideal and pretty much limits what you are going to be able to do, whatever rig you have, so don’t get too carried away with sail area or too ambitious about sailing performance until you have got a feel for what you are about.

    I don’t have a reputation to lose so I will venture an opinion on sail area by referring you to the website https://www.nztya.nz/trailer-yacht-designs.html where you can see a brief summary of about 150 designs of trailer yachts, some of them roughly comparable with your boat’s length and displacement, and you might see that some of the smaller ones have a sail area of around 12-15 sq m.

    But these boats have their weight distributed much more sensibly for sailing than you, so I think you might be advised to try the idea first with quite a bit less than that and just see how you get on.

    Be safe and have fun.


    (I can't help adding this - there hasn't been much response apart from Annie and it might be a bit unfair to expect the junk experts to come up with a one-iteration step that will take you straight to an optimal plan for mast and rig - which is maybe what you are hoping for - when you are presenting such an out-of-the-ordinary platform to start with. That doesn't mean for one minute that it can't be done, but maybe you should be thinking of getting there step by step and just enjoying the journey. Or maybe you might decide to look around for a trailer yacht (do you have them? We have heaps of them here in New Zealand and they can be had cheap here now - Mauritius sounds like an ideal place for such a boat.) Putting a junk rig on an old trailer yacht would bring you a flood of good advice from experienced people who have done that very successfully. You can still have a small outboard  motor. Have two boats - one for sailing really well under junk rig - and one for exciting fun under power!)



    Hi Graeme and thank you for your generosity with your time and advises. Some quick answers to your above comments, not necessarily in their initial order.(1) My mind is set on a junk rig for the many reasons that both you and I know which I wont list. (2) Two boats are not an option because of the high cost of renting an additional berth at the marina (the only marina in Mauritius!). (3) I don't mind being snubbed by the experts, and I agree with you that the best route for me to take is an iterative design approach. Trial-and-error mixed with determination and common sense can go a long way. Having said that, I would like to avoid the major (and potentially unsafe) blunders of the novice JR converter. You already answered 90% of what I was looking for, namely whether this hull can sail with a junk rig or not, and I thank you for it.

    There a re a few locals that repair kitesurf and windsurf sails, and I can have a relatively inexpensive undersized  lateen sail made, to try out the boat behavior. Another advantage of the tabernacle design on a reinforced bow deck, is that in the event of a truly unbalanced helm, I can probably adjust the mast position without major structural changes.

    Also, you are absolutely right about being able to rig a boat in case of an emergency, and this is also the reason I am readying this boat to sail. I am not exactly what you call a 'prepper', but consider this: Mauritius has 1.2M people and ranks 19th in world population density. The island imports almost all its food and energy from abroad. Having an autonomous exit pod in case of real emergency hardly seems superfluous.
    Last modified: 19 Jul 2017 07:42 | Deleted user
  • 19 Jul 2017 02:25
    Reply # 4983571 on 4976050
    Anonymous member (Administrator)

    Dom, just to make it clear, any opinion I might have about JR is of little value because I am in the beginner category with that particular rig, same as you. All I can tell you about that is that you are in the right place to get the best advice, if that’s the rig you want to go with.

    What I meant to say is that with a bit of improvisation you can have some fun learning how to make that very nice motor boat sail, if you want to. You might be still a little distance away just yet from knowing what sort of rig you want – if indeed you even really want to sail - so why not just start with a simple home-made lug sail on a mast you can lift in and out, and a blade you can lash onto the outboard leg.

    Imagine you are lost at sea with a broken-down motor and have to make a jury rig with what is available and at hand. You will be able to make that thing sail alright, that’s for sure. Pick your weather, have some fun and see what you can learn. Its called “messing about in boats….” its all good fun and that might be as far as you decide to go with it.

    That hull shape won’t stop you from being able to sail moderately well, even to windward with a bit more lateral plane, which does not have to be a foil. But just don’t forget that if you have to carry that motor, then quite a big chunk of your total weight is right at the back and up over the waterline which is far from ideal and pretty much limits what you are going to be able to do, whatever rig you have, so don’t get too carried away with sail area or too ambitious about sailing performance until you have got a feel for what you are about.

    I don’t have a reputation to lose so I will venture an opinion on sail area by referring you to the website https://www.nztya.nz/trailer-yacht-designs.html where you can see a brief summary of about 150 designs of trailer yachts, some of them roughly comparable with your boat’s length and displacement, and you might see that some of the smaller ones have a sail area of around 12-15 sq m.

    But these boats have their weight distributed much more sensibly for sailing than you, so I think you might be advised to try the idea first with quite a bit less than that and just see how you get on.

    Be safe and have fun.


    (I can't help adding this - there hasn't been much response apart from Annie and it might be a bit unfair to expect the junk experts to come up with a one-iteration step that will take you straight to an optimal plan for mast and rig - which is maybe what you are hoping for - when you are presenting such an out-of-the-ordinary platform to start with. That doesn't mean for one minute that it can't be done, but maybe you should be thinking of getting there step by step and just enjoying the journey. Or maybe you might decide to look around for a trailer yacht (do you have them? We have heaps of them here in New Zealand and they can be had cheap here now - Mauritius sounds like an ideal place for such a boat.) Putting a junk rig on an old trailer yacht would bring you a flood of good advice from experienced people who have done that very successfully. You can still have a small outboard  motor. Have two boats - one for sailing really well under junk rig - and one for exciting fun under power!)


    Last modified: 19 Jul 2017 05:55 | Anonymous member (Administrator)
  • 18 Jul 2017 15:54
    Reply # 4982508 on 4982504
    Deleted user
    Dom Lang wrote:
    Graeme Kenyon wrote:

    I thought that might be the case (about wanting to leave the motor in place.)

    Well, with that motor you won't need to be too worried about having to sail to windward anyway. I am sure you could have a detachable blade to convert the outboard into a rudder (at least while the engine is not running!) and have enough fun running and reaching when the wind is fair, to justify the trouble of fitting a little rig. Just about anything will sail well enough to have fun, and the shape of your hull is not at all out of the question. It is not uncommon to see motor boats being given some kind of auxiliary sail and if you are not too worried about going to windward - and not reliant on it - just put a simple rig on it and don't get too technical about it. Scows and barges and similar work boats don't exactly have ideal hull shapes for sailing either, but in the days of sail they did the job well enough. Most people these days would be surprised at how well a clumsy old deck scow will sail, just for one example. By comparison, your hull shape is much more like a modern sail boat even though not ideal. Just keep safety in mind - apart from that just keep it simple and have some fun. I can't see why you have to have a stainless steel tabernacle but I will leave all that to the experts. 


    Thanks Graeme. The tabernacle is for lowering the mast. I have a 3.8m clearance bridge to go under to get out of the marina.

    To summarize where we're at on this thread:
    • I posted some pics of the boat. its 5.8m long and bare hull weight is 400Kg.
    • Graeme's opinion is that my conversion to JR can be done. (I agree :)
    • I need some suggestion about the sail area. Anyone?
    ... and take it from there.
  • 18 Jul 2017 15:48
    Reply # 4982504 on 4982447
    Deleted user
    Graeme Kenyon wrote:

    I thought that might be the case (about wanting to leave the motor in place.)

    Well, with that motor you won't need to be too worried about having to sail to windward anyway. I am sure you could have a detachable blade to convert the outboard into a rudder (at least while the engine is not running!) and have enough fun running and reaching when the wind is fair, to justify the trouble of fitting a little rig. Just about anything will sail well enough to have fun, and the shape of your hull is not at all out of the question. It is not uncommon to see motor boats being given some kind of auxiliary sail and if you are not too worried about going to windward - and not reliant on it - just put a simple rig on it and don't get too technical about it. Scows and barges and similar work boats don't exactly have ideal hull shapes for sailing either, but in the days of sail they did the job well enough. Most people these days would be surprised at how well a clumsy old deck scow will sail, just for one example. By comparison, your hull shape is much more like a modern sail boat even though not ideal. Just keep safety in mind - apart from that just keep it simple and have some fun. I can't see why you have to have a stainless steel tabernacle but I will leave all that to the experts. 


    Thanks Graeme. The tabernacle is for lowering the mast. I have a 3.8m clearance bridge to go under to get out of the marina.
  • 18 Jul 2017 15:39
    Reply # 4982447 on 4976050
    Anonymous member (Administrator)

    I thought that might be the case (about wanting to leave the motor in place.)

    Well, with that motor you won't need to be too worried about having to sail to windward anyway. I am sure you could have a detachable blade to convert the outboard into a rudder (at least while the engine is not running!) and have enough fun running and reaching when the wind is fair, to justify the trouble of fitting a little rig. Just about anything will sail well enough to have fun, and the shape of your hull is not at all out of the question. It is not uncommon to see motor boats being given some kind of auxiliary sail and if you are not too worried about going to windward - and not reliant on it - just put a simple rig on it and don't get too technical about it. Scows and barges and similar work boats don't exactly have ideal hull shapes for sailing either, but in the days of sail they did the job well enough. Most people these days would be surprised at how well a clumsy old deck scow will sail, just for one example. By comparison, your hull shape is much more like a modern sail boat even though not ideal. Just keep safety in mind - apart from that just keep it simple and have some fun. I can't see why you have to have a stainless steel tabernacle but I will leave all that to the experts. 

  • 18 Jul 2017 14:59
    Reply # 4982369 on 4982164
    Deleted user
    Graeme Kenyon wrote:

    I just looked at your photos and, hey, this is not a crazy idea. I am sure Annie and the others can give you good advice on junk rig design, and the best way of achieving lateral plane - but I can't resist hopping in first to say that she is quite a lovely looking boat, not the sort of thing we normally expect to see on the front end of a 65hp engine and I bet she does not need anything like that amount of power to scoot along. The forward sections and entry are lovely - just what a sail boat should look like. Aft, she carries those full sections right to the back, necessary to absorb the power and carry the weight of a motor, but not quite so good for sailing. I think if you left the big motor at home when sailing, just carried a light auxiliary instead (you are going to need a rudder back there anyway), and trim her a little down at the bow, (or, rather, lift that big back end up a little) she would sail well enough. If it were me I would fit either a centreboard case, a little further forward than usual to match the trim - or just add a few inches of permanent draft (if that does  not interfere with launching and retrieving) by way of a full length deadwood keel of just a few inches, because those two ways are all I know. I have no doubt there are other ways of getting a  bit of lateral plane which you will need if you want to sail to windward, and other people might have better ideas how to achieve that. Don't let anyone sneer at the idea of a full length deadwood keel though- a very easy addition, because although it might not get you the best windward performance, even just a few inches will give you some, enough for a moderate sail area, as I did a dinghy sailing conversion that way a few years ago and it was easy and I thought it worked quite well. That won't really detract from its performance under power, either.

    An interesting and unusual challenge for the junk aficianados and worth a bit of thought. Good luck.


    Dear Graeme, Thanks for the prompt comments and for your time looking at the pics. This boat+engine is fantastic on the lagoon. It can fly at over 25kts and takes the family and friends to the most remote areas regardless of the tide. Its very sturdy and requires little maintenance.

    I hear you about the weight of the motor, but that is precisely why I cant remove it. Its way too heavy and its all connected to the hydraulics. I toyed around maneuvering the boat downwind under wind power, by lowering the (now removed) canopy like a small spinnaker, and stirring with the engine. It worked quite well and I suspect that with the addition of some lateral resistance on the immersed portion of the outboard engine, I can stir her fine. Life is a constant dilemma about making the right compromises, and with this conversion, my aim is to minimize the time and efforts that will be needed to switch back and forth between sail and motor modes. That probably means lowering my ambitions to sail closely to windward. The direction of the prevailing winds relative to my navigation zone should work in my favor. For lateral plane, if that became a real issue,  I was thinking about sliding a used kite-board down vertically on the sides.

    Knowing very little about sail boats, I have some anxiety about choosing the right material for the unstayed mast. I read that aluminum poles (tapered or not) should work. Also, if anyone could advise me on setting a sail area for this boat, that would be great. I was thinking about 10sqm: does that sound right? From that I can infer the characteristics of the mast I suppose... and look at strengthening the deck where the tabernacle will be mounted. Thanks everyone!
    Last modified: 18 Jul 2017 15:21 | Deleted user
  • 18 Jul 2017 12:39
    Reply # 4982164 on 4976050
    Anonymous member (Administrator)

    I just looked at your photos and, hey, this is not a crazy idea. I am sure Annie and the others can give you good advice on junk rig design, and the best way of achieving lateral plane - but I can't resist hopping in first to say that she is quite a lovely looking boat, not the sort of thing we normally expect to see on the front end of a 65hp engine and I bet she does not need anything like that amount of power to scoot along. The forward sections and entry are lovely - just what a sail boat should look like. Aft, she carries those full sections right to the back, necessary to absorb the power and carry the weight of a motor, but not quite so good for sailing. I think if you left the big motor at home when sailing, just carried a light auxiliary instead (you are going to need a rudder back there anyway), and trim her a little down at the bow, (or, rather, lift that big back end up a little) she would sail well enough. If it were me I would fit either a centreboard case, a little further forward than usual to match the trim - or just add a few inches of permanent draft (if that does  not interfere with launching and retrieving) by way of a full length deadwood keel of just a few inches, because those two ways are all I know. I have no doubt there are other ways of getting a  bit of lateral plane which you will need if you want to sail to windward, and other people might have better ideas how to achieve that. Don't let anyone sneer at the idea of a full length deadwood keel though- a very easy addition, because although it might not get you the best windward performance, even just a few inches will give you some, enough for a moderate sail area, as I did a dinghy sailing conversion that way a few years ago and it was easy and I thought it worked quite well. That won't really detract from its performance under power, either.

    An interesting and unusual challenge for the junk aficianados and worth a bit of thought. Good luck.

    Last modified: 18 Jul 2017 12:43 | Anonymous member (Administrator)
  • 18 Jul 2017 10:42
    Reply # 4982069 on 4977163
    Deleted user
    Annie Hill wrote:

    Hi Dom and welcome to the JRA. I suggest that the first thing you do is to take a few photos of the boat, out of the water, showing its profile and put them in a photo album you can create in your profile. Also we need to know the weight and dimensions. At first glance, an 18 ft boat that carries a 60 hp outboard doesn't sound the most likely candidate for a junk, but with more information, people will be able to make a better judgement.

    Mauritius sounds like a lovely place to live. Lucky you :-)



    Dear Annie, Thanks so much for taking the time to reply to my post. I took the opportunity to do some homework and start doing some research on the subject. I posted some pictures as you suggested. 'AKULA' is 5m80 long. The bare hull weight about 400kg. The boat is in a marina and needs to go under a 3.8m clearance bridge. Apparently this hull can be converted to sail. What do you think?

    From what I gathered so far, I would need to reinforce the bow deck and mount a tapered aluminum mast on a SS tabernacle.

    Mauritius is indeed a nice place. Consistent winds over half the year - especially during the austral winter, but very few areas for mooring a large keeled boat. The few mooring spots are the commercial harbor in Port-Louis (noisy and industrial), and a few river mouth bays. Riviere Noire at the SW is a popular one. Most people here have motor boats and cruise in the lagoon. Others have expensive catamarans  for day sailing in the lagoon or outside along the reef. We are also in a cyclone prone area and few people venture far in the open sea during the austral summer.
    Last modified: 18 Jul 2017 10:57 | Deleted user
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

                                                              Site contents © the Junk Rig Association and/or individual authors

Powered by Wild Apricot Membership Software