O'day Daysailer ll Mod and Conversion

  • 23 Dec 2022 23:27
    Reply # 13034522 on 13021193
    Anonymous member (Administrator)

    Bill wrote: The Johanna sail doesn't seem to work with my new mast position...

    A very rough eyeball "plonk" and it looks pretty good to me. Shorter mast and more area - what's not to like?

    You had better put up your original scale drawing of the DSll, with a scale rule on the drawing, and your new preferred mast position marked in  - and ask Arne for his advice on a Johanna rig. It is pretty adaptable in a variety of versions and I find it hard to believe it wouldn't fit.

    If you are re-considering a SJR I wouldn't design a new one,  I'd recommend you make a scale copy of the Amina Mkll rig - its pretty much in the public domain now, but still you should contact Slieve and ask him for his permission and advice. You can discuss the fundamental parameters (jibs and mains cambers, and sheeting angle).

    AR can be altered by simple scaling with x and y axes unlinked - but I wouldn't alter it. (Better still, perhaps for a dinghy, simply removing a lower panel pair and re-scaling for area, because I have no idea how those jibs would respond if you alter THEIR AR which is what would happen in that first suggestion. I just wouldn't alter the proportions of that sail at all! You might consider Arne's Hasler/McLeod SJR which is a little different in some respects but, as yet it's untried.

    I guess the question of the moment is - can I put a lowish AR SJR (145-ish ft2 SA) on this boat with my new desired mast position?  I would consider the Amiina Mkll as already lowish AR, or very moderate. But, in any case, your new desired mast position is too far forward for it I believe. To put a 33% balance sail on your new desired mast position would probably need an extreme ultra-low AR, I can't imagine it, far better a Johanna sail is my gut reaction. I'll try to draw something and see what it looks like.

    [edit: I tried and I don't believe it can be done. Your only option would be to reduce the area a little, and add back that area with a slightly offset mizzen at the stern and a long boomkin - like some of JW's designs. Something like this might work, but only if you actually want a yawl rig, then I think it might be quite good.

    Make a sprit boom leg-o-mutton mizzen, absolute minimalist sail - (just a flat triangle, self-vanging and you can adjust the camber with the snotter) and you won't get much better sailing than this... (click, switch on the sound...)

    I haven't done any calculation. The mizzen might need to be slightly bigger in the above sketch. You are capable of drawing that up yourself and trying different combinations and calculations - but starting to turn a simple conversion into a monster again if not careful.

    A yawl might be fun, and there is some merit in it ... but...if it's just because you like that mast position then first I'd talk to Arne about a Johanna sloop rig. Try to keep things as simple as you can and change as little as possible.]

    Last modified: 24 Dec 2022 21:11 | Anonymous member (Administrator)
  • 23 Dec 2022 22:31
    Reply # 13034490 on 13021193

    Welcome back to the Graeme and Bill show . . . 

    Hey, I'm reconsidering the SJR. The Johanna sail doesn't seem to work with my new mast position.. Arne's design is pretty well locked-in with AR and SA if mast position and CE cannot be moved, am I right? So, without changing mast position or CE I end up with too small a SA or too high an AR. 

    And so, I'm not really finding info on how to draw an actual SJR. I read through all Slieves stuff but he doesn't really give you specifics as to how actually design the sail . . . or maybe I need to re-read.  But, can you throw me some links or info on how to do this? Thanks! 

    I guess the question of the moment is - can I put a lowish AR SJR (145-ish ft2 SA) on this boat with my new desired mast position? 

    Last modified: 23 Dec 2022 23:02 | Anonymous member
  • 23 Dec 2022 00:22
    Reply # 13033716 on 13021193
    Anonymous member (Administrator)

    Stepping the mast (and setting up the rig)

    2kUS for a mast would be unaffordable for me, but if you can get a carbon fibre mast - good - that's the best for a number of reasons. Whether you can easily raise and lift it with all its masthead running rigging in place (as it would be), keep it vertical and thread it down through the partners all the way to the keel step is not a trivial exercise for a mast that length. Will you be standing alongside the dinghy (on its trailer) while you do it? (I've seen it done that way, on a Paradox, but I wouldn't be able to do it). Or will you be doing it from up on the deck, presumably with the boat still on its trailer? (I'd get vertigo).

    I think these are matters which you can figure out later and are perhaps not crucial to decide at this stage, but you might mull over ways of stepping the mast.

    Things to think about while enjoying the Christmas festivities.

    I dare say you are younger than me, but don't write off the idea of some kind of tabernacle.

    And then you've got the task of setting up the sail bundle each time you launch the boat. Use clip-on standing parrels I suppose, and try to keep the sheetlets/mainsheet spaghetti tidy and untangled.

    The very simplest kind of dinghy "tabernacle", which I think (when I get a round tuit) I might try on my Golden Bay dinghy, with its somewhat shorter mast , is a simple over-diameter tubular housing which stays permanently in place and sticks up above the deck as high as necessary (even above the normal level of the boom, if necessary to clear a cuddy), into which a light mast can be simply slid down - that is, if the mast is manageable enough to be lifted and held vertical long enough to get it in and started. It won't make raising the mast much easier, but I have the idea that the furled sail bundle (which otherwise would be somewhat time-consuming to set up each time) can be left in place permanently in its parrels on that stumpy "tabernacle" tube - also with sheetlets and mainsheet already rove. Then all that would be needed to go sailing is to drop the mast in and lock it (already dressed with its masthead running rigging), clip on the halyard and standing lifts - and you're ready to raise sail and go.  As near as you could get to the situation on a moored boat. I've never seen it done. [Edit: in a later post, Arne has suggested the same idea with his "Tube type mast socket", and also confirmed that the mast will be light enough to plonk in place. In that case I think this is definitely the best kind of tabernacle for a dinghy. Managing the sail bundle that way, with all its sticks and string, will be a godsend. Make sure the mast locks in place when dropped into the tube, so it can't rotate. Junk rig imposes rotational forces on the mast which may be inconvenient.]

    A conventional forward-opening tabernacle would probably set the rig too high above the cuddy,  (as you have already observed) unless you cut some sort of trunk or case into the deck to allow the heel of the mast to swing down below deck level. That's all too much trouble and time to be worthwhile, probably, on your boat, and I don't suggest it. (And, by the way, you wouldn't want the kind where a pin goes through the mast. That's a weakness at the weakest point. The pin abaft the mast is better, in a free-standing rig. For a small dinghy I would put the pin through the tabernacle itself, just aft of the mast - and use a square lashing for the hinge. Never seen it done, but I can't see what would be wrong with a rope lashing, for a dinghy).

    There is a type of hinge arrangement which has a sliding outer tube which slides down over the tubular internally-hinged mast, when the mast is up. Personally I don't like that idea at all, but evidently it does work. 

    For a camper cruiser I still like my "hingeless" heel hinge in which the mast is stood up from the heel and into the partners then locked in place with a gate at the partners. Much easier than picking it up bodily and trying to drop it down through a hole in the deck. But that only works if the cabin top is open.  The open top in itself has other advantages in a dinghy, and a removeable canvas top (or quick clip-on canopy) is not too difficult to make. Well, I've thrashed that idea already, but since you intend to modify the cuddy top, I mention it again and suggest consider it.

    (The first of the two main advantages of the junk rig is: incredibly simple reefing and handing, especially when single handed, and you can raise sail, hand, reef or unreef without even having to be head to wind. You don't even have to stop the boat to do it. But the downside is - the "price you pay" - the rig is a bit more complicated to set up initially, ideally suited to being permanently set up on a moored boat and not so ideal if it needs to be dismantled and re-assembled at each outing. There's ways of speeding things up, I've got mine reasonably quick now.

    One day maybe someone will start a thread on easy mast raising and super-fast ways of setting up a junk rig, for trailer boats, as there seems to be a bit of a trend these days towards smaller, trailerable sailboats.).

    Ballast would be helpful, even if minimal, better than none. Perhaps, especially in the deeper-bodied narrow-on-the-waterline type of boat that is designed for it - less so for yours I think - you might find you have enough weight already without ballast, but maybe you can keep the option of trying it. As an alternative to pumping and discharging seawater, and much easier to fit than making water ballast tanks, I have considered packing bags of wet sand (off the beach, and leaving it behind afterwards). Wet sand would be a bit more effective than water, as ballast. And that way you could try a bit of ballast in your boat and see how it works out, without having to commit to any major modification. Would just need to be lidded down and secured under the floorboards, along with your water bottles, tins of balked beans, cans of beer etc). Again, never seen it done. More things to think about later.

    Last modified: 27 Dec 2022 23:21 | Anonymous member (Administrator)
  • 22 Dec 2022 22:59
    Reply # 13033669 on 13021193

    Maybe we're on the same page, but to clarify, the mast will be stepped to the keel, and where it goes through the cabin top will be reinforced partners. I'll probably put a ring frame there too (dotted line in drawing), and there's a nice existing stringer there as well that will help tie everything together. Should be super strong without adding much weight. Building up the aft of cabin from existing trunk will be easy.

    Solo stepping of the mast: seems any kind of tabernacle would just be a major compromise. I'm blessed to have a business in my area that custom makes tapered unstayed CF masts, and they're surprisingly affordable (around 2k US). So I'm assuming I can "man-handle" such a lightweight mast (20-25 Lbs) on my own? Probably right around 20' in length/height. 

    I have not thought about control lines and their location yet :) thanks for the heads-up.

    Funny, I watched those JW vids the other day. The long interview vid is super insightful. And yes, it's all about recovery from capsize, gotcha. For buoyancy, I'll want to look into it more. But from what I gather the closer we get to an egg with an air pocket the better . . . and double air pockets in the ends (ala modern ocean row boats) is even better. Ballast would be helpful, even if minimal, better than none.

    I got the CLR with the cardboard cutout and balance method using half the width of the rudder. Accuracy is questionable. But I feel good about the accuracy of my CE calculation, so no worries, yup. 

    Back to wrapping my head around Arne's math . . . 

  • 22 Dec 2022 20:12
    Reply # 13033559 on 13021193
    Anonymous member (Administrator)

    I don’t think your raised cabin would necessitate raising the mast. It would be necessary, however, to have the top open (birdwatcher style) if you were to use SJR with running parrel downhauls. However, since you have decided to place the mast a little further forward and have a Johanna rig, then that’s not an issue and I think the boat will look very good, your mast will be a little shorter with the Johanna rig, and you will know that you have a rig which is well understood and known to perform well.

    Assuming the original cuddy top is strong enough to support the mast (laterally) then raising only the aft part of the cabin seems rational in some respects. My only question is: how do you intend raising and lowering the mast, as I assume the boat will be trailered and this is something you will do each time the boat is launched. I like the simple arrangement for mast raising that I have on Serendipity, with the open cabin top, but there are a number of other possible answers to that question.

    Also, I am not sure if there are structural considerations, but if you could avoid having that step in the cabin top, it would make things simpler when it comes to leading halyard and control lines back to the cockpit. It's all good, these are just details you need to have thought out.

    I can’t comment on your proposed buoyancy layout as there is no plan drawing and your description is not clear to me. In any case, it is outside my competency. I think John Welsford has competency in this area and has written/spoken at length on this subject, for example, here is a presentation (hosted by dinghy aficionado Roger Barnes: “designing boats fit for purpose” The buoyancy won’t prevent possible capsize or swamping (which hopefully will be unlikely anyway) but the idea is to make it possible for you to recover from this situation should it arise. Buoyancy is therefore not just a matter of convenience/volume – its placement is important, and consideration should be given to how the boat will float in a flooded state, and how stable it will be when fully capsized. (In the swamped state it should be stable, but in the capsized state you want the stability to be negative or as close to zero as possible). Watertight tanks placed low can be used for stowing heavy things, up under the deck can be kept empty or used for stowing lightweight things. I guess you can figure all that out. Here is the video specifically on the subject of buoyancy, capsize and recovery   Note the value of a buoyant mast.

    I don’t know how you have calculated that CLR, it looks too far aft to me, but it doesn’t matter because it’s irrelevant anyway. You can decide where to place the geometric centre (CE) of the junk sail simply by paying attention to the designed bermudan CE. The junk CE might not coincide with the bermudan CE (as it would have with done SJR) but the designer of your rig can advise on any adjustment which may be necessary. Also, it is not so critical on this little boat – within reason, you can over-ride any imbalance by shifting your weight fore and aft, and adjusting the centreboard, as is normal in dinghy sailing. You will find when changing from sailing to windward, to sailing down wind, moving your weight fore or aft will naturally help to maintain helm balance.

    Its good that you are keeping weight down and modifications to a minimum. It's starting to look like a plan.

    Last modified: 22 Dec 2022 23:15 | Anonymous member (Administrator)
  • 22 Dec 2022 17:23
    Reply # 13033383 on 13021193

    And here's scale drawings of the original DS ll and my new modded version with raised cabin and lazarette.

    Mods allow for buoyancy fore and aft (watertight hatches), and seating room inside (out of the elements . . . current cabin is too low to sit up in, feels like a coffin inside). Also, with the addition of the lazarette, the cockpit size will be greatly reduced, so swamping will be nearly impossible. Swamp-age will also be reduced because the area on top of the CB trunk will be "shelved" making a platform for rowing and more storage below, again, watertight. I'm singlehanded and don't need such a large cockpit. 

    Sleeping space is easy as is, there's plenty of room (6'+) on either side of the mast to lay down (I'm short).

    The JR mast is a bit forward conveniently placed to allow for easy conversion using the existing structure with sufficient bury, while allowing room for the cabin mod and seating. 

    FYI, I'm an artist, not and engineer :) 

    2 files
  • 22 Dec 2022 15:18
    Reply # 13033244 on 13021193

    Very cool Graeme, thanks for the drawing. That's a nice sail shape, I like it. However, I think you helped me realize that the split won't work hahaha. Mostly mast position, and then like you said, clearance for downhauls would raise things maybe too much. I should mention, I'm still planning to raise the roof on the cabin a bit, and of course this would raise the sail, CE and increase mast height more than makes sense I feel. I'm looking to keep heeling and rocking to a minimum, if that makes sense . . . 

    I'm working on some more subtle mods for the hull that will greatly increase the practicality of this boat while making it much more seaworthy and adding negligible weight. The mast indeed needs to be a bit forward of the original, and so I'm looking at Arne's sail design . . . might be the best option. 

    I'll be back here soon with new drawings. Cheers! 

  • 19 Dec 2022 21:40
    Reply # 13030333 on 13021193
    Anonymous member (Administrator)

    ...I sold the Bermudan rig as soon as I bought the boat...

    OK. So, first decision: where to put the new mast.

    Rough shot with a ruler on the computer screen - with SJR you might just about get away with using the original mast position. (This tends to happen with 3/4 rigs ie where the bm rig has a smallish fore-triangle - I think it was the same with Dave D's Wayfarer cruising dinghy).

    (Which, have a look at that Wayfarer, its in JRA Mag 79. While you are at it, download Magazine 80 and have a look at River Rat. And then, while you have magazine 80, you might as well add to your list of choices by looking at a soft wing junk sail, David Tyler's Weaverbird, also magazine 80. This would put your mast furtherest forward of all rigs.)

    Amiina Mkll option

    You might be better off with the mast further forward (ie a Johanna rig or similar) depending on how you want to lay things out.

    The first problem I can see with the SJR is that there is not enough room between the boom and the cabin top for the spanned running parrel downhauls - a feature of the Amiina ll rig (and a good feature.) You need more than half the width of a panel for the spans.

    I had the same problem with Serendipity, but did not become aware of it until it was too late and I had already made the sail and the mast. There's always a way around any problem. If you want to have your mast in that position, then I can think of three solutions:

    (1) open up the cabin top (like a Bolger Bird Batcher style) - that's essentially what I did - so the downhauls go all the way down to a turning block  below the level of the cabin top. The open-top cuddy also facilitates easy raising of the mast. You won't need a tabernacle in that case (although I made a rear-facing heel-hinge tabernacle anyway). However, its messy in some ways, although personally I quite like it now - I can walk right up to the mast. I just made a removeable canvas top for the cabin, for night time, and usually leave it open when sailing. (This option might be a head-scratcher if your cabin top is made with foam or balsa core.)

    (2) forego the spanned parrel downhaul system and use conventional parrels - would be a bit of a pity, perhaps? I don't know enough to advise on this option.

    (3) have a look at Arne's hybrid Hasler/McLeod split rig - it has narrower panels so you might be able to use shorter downhaul spans. And you could have a slightly shorter mast for the same sail area. You'd be pioneering - and you'd need to check with Arne if he thought the rig might be better with conventional batten parrels anyway. I have no idea about that. Anyway, its an option I would consider, if that's where the mast needs to go.

    You also need to consider structure. You are converting over to a free-standing mast, ie a keel-stepped deck-supported structure. I beefed up the cabin top a little, in the way of 'partners' though I don't think much is needed on a very small fibreglass boat. In some ways structural considerations point towards putting the mast in front of the cabin top and just beefing up the foredeck a little. This might suit your sleeping and storage arrangements better, too. But then you need to consider how you are going to step and unstep the mast, or whether you are going to make some sort of keel-stepped tabernacle. It's doable, though you will need minimum 10% length of mast buried in the tabernacle - make an accurate drawing and make sure the boom is not then going to be too high.

    (All deck modifications will be problematic if your deck is foam or balsa core. I hope it's not. You can't just bolt things through or onto that. You might have to get creative).

    So there are your first practical problems to chew over. The details of what I did on Serendipity can be found here. But I would definitely suggest you have a discussion with Arne. All things considered, the Johanna rig might be the better way to go. Or, you might be able to make contact with David T, the Weaverbird Mk1 plan form might appeal to you, especially if you lean towards higher aspect ratio - that's the predecessor to the soft wing sail so you might consider both. (David has probably designed more different types of junk rig and made more sails than anyone). Paul T who is a sail designer and sail maker here in New Zealand has developed a semi-fanned cambered sail which appeals greatly to the eye and would be nice if you want a low AR sail - it looked good on Freebie I thought. (You can get an idea of what it looks like from this). (Very low balance so mast would be well forward. I love it, but a low balance/low AR cat rig might be a bit of a handful on your boat, at first, until you have learned how to tame it). 

    In my opinion these, together with Amiina Mkll represent the pick of all the modern variants. The reason I keep coming back to Amiina ll is because I know it works, but its the only junk rig I know from direct experience. You need to get some dialogue from other people now.

    The mast position might determine the rig - or vice versa.

    You pays y'r money and takes y'r choice!

    One last thing: it's hard doing your research when you have to find old magazine articles and/or plough through endless tedious forum posts. The JRA website search engine does not filter very well. There is now a prototype improved search facility which might be useful to you and help you catch up with archived information. Its called the JRA knowledgebase and for the moment, courtesy of James G, you can access it here.

    Last modified: 20 Dec 2022 05:53 | Anonymous member (Administrator)
  • 19 Dec 2022 15:27
    Reply # 13029871 on 13021193

    Well, I haven't found you to be self-indulgent. It's important to see each others personalities in this digital realm. 

    Alas, I sold the Bermudan rig as soon as I bought the boat. I'm all-in baby! 


  • 19 Dec 2022 02:16
    Reply # 13029451 on 13021193
    Anonymous member (Administrator)

    I am sorry I wrote those long spiels. It was self-indulgence really, and it probably hasn’t helped. Maybe it's put other people off from bothering to chime in. If so, I really am sorry.

    Bill, you are over-thinking. I tend to do that too. I rather like James G’s expression “analysis paralysis”.

    Just watch those video clips of the O’Day in cruising mode.

    You have got a O’Day DSll – not quite the most ideal or perfect for camper cruising, but from the video clips you can see that it is certainly adequate in most respects and very good in some.

    Whatever rig you put on it, that same thing will apply to the rig. If you look at the other boats in the background of those youtube clips, the most striking thing they have in common is that they are all quite different from each other, and all rigged differently – yet their owners are grinning from ear to ear (including the O’Day owner whose boat is sailing rings around all of them).

    Cruising is not about having the “best” solution to everything – its about being resourceful and making the best of what you have. To begin with, just avoid extremes or anything radical. If your boat already has a complete set of rigging, then I would strongly advise just make sure you have a system for reefing and ensure you know how to use it – that’s the only essential modification that might be needed – and just go sailing in it. Don’t waste time and money creating a monster at this stage. Spend a season exploring the little islands and bays you describe, organising your little stove, sleeping bag, inflatable mattress, and boom tent, white plastic bucket, oars and whatever safety gear is appropriate. Before heading off too far away on your own, get the feel of the boat and how it behaves in a bit of wind while under reduced sail – and/or sail in company with other boats for a trip or two, if that is possible. After that first pleasant season getting to know the boat, spend a comfortable winter planning your junk rig conversion – or designing your dream mini-voyaging boat. That’s my advice.

    The junk rig is not a goal, it's just a means to an end. But if you want to skip that first season and put a junk rig on the O’Day straight off, then first figure out where you are going to cook and sleep, then the best mast position from what remains, considering structure etc - and determine from that what the “balance” of the rig will need to be. The maximum is about 33% and if as high as that, then you might have to look at a split rig. Less than 30% and it should be the usual sort of contiguous sail – and that might be best as it might give you a little more flexibility in the final process of getting mast rake and sail balance “just right”. My personal opinion is to follow what is the convention these days and use rigid battens, and build some camber into the sail. Don’t try to follow too many different opinions. Dip into Practical Junk Rig by Hasler/McLeod, it’s the “bible” (Old Testament actually). (Your initial drawing showing a sheeting envelope – it's rare but very good to see that - tells me you already have). Read Arne’s notes at least twice. Don’t go for extremes in regard to aspect ratio. Utilise whatever materials are readily to hand, or whatever matches your skill sets. The DSll existing mast height and sail area will give you a rough guide to the numbers. If you like the Johanna rig, you could reduce mast height a little while increasing the sail area just a little. But don’t go overboard with sail area on that boat, no need, concentrate more on not adding too much weight to it.

    Perfect is the enemy of good. Just stay safe and see how much you can learn from practical experience, while having a bit of fun at the same time.

    Maybe somebody else can tell you what is the “best” rig for a O’Day DSll,

    I've said far too much already.

    Last modified: 19 Dec 2022 05:33 | Anonymous member (Administrator)
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