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Thread: Whisstock design #146: potential keel variations

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    Default Whisstock design #146: potential keel variations

    One of the designs I am looking at for my first boat build is the Whisstock 146 (as a gaff sloop, probably). However, on a small pocket-cruiser under 19' long, I would really like to avoid having a centreboard casing taking up the centre of the small floorspace. Around here (East Anglia, UK), there are lots of bilge keelers, as we have estuaries and large tidal ranges. Boats can often settle on the mud when moored, or find themselves in really shallow water when moving, so bilge keels work well. Centreboards are favoured over daggerboards I understand, because of the high chances of running aground. However, my boat will be a trailer sailer.

    One of the other designs I have been looking at is Selway Fisher's Evening Swan, which has bilge keels as an option. There is also a centreboard option. This is a heavy boat, though, and I'm cautious about something weighing 1.2 tons as whatever I build will live on a trailer.

    I contacted George Whisstock of this parish by email, and he said that he could redesign the hull to work with bilge keels, or, he suggested, how about an off-centre "centreboard"? Instinctively, having the symmetry of the hull messed with in that manner leaves me feeling a little woozy, but I understand that it works perfectly well hydrodynamically.

    So I am after some learned advice from the good folk of the forum as to the pros and cons of any of these changes. George said there were implications for the draught of the boat and for the centreline (if I understand correctly), in adding bilge keels........and I have no idea how the junction between clinker planks and the bilge keels would work (I may strip plank whatever I build, anyway). If anyone has any wisdom to guide my thinking, I'd be most grateful.

    Finally, if anyone knows anyone who has built either a 146 or a 119 that I might be able to look at before embarking on the project, do please let me know.

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    Default Re: Whisstock design #146: potential keel variations

    Have you considered an Eun Mara?

    Looking aft, bilgeboards keep the center of the cabin open while allowing for (relatively) easy trailering and beaching

    She's 19'-9" LOD with a 6'-8" beam
    Steve

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    Default Re: Whisstock design #146: potential keel variations

    Trivial, I know, but I don't want a double ender, and it's a bit too long. It's a gorgeous boat, but I'd also discounted it on the grounds of it being clinker built, which I had initially chosen to avoid. However, I've been won around on that score and am looking afresh at clinker designs I might have dismissed previously.

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    Default Re: Whisstock design #146: potential keel variations

    You need to build the boat that calls to you, if some stodgy transom-sterned boat does that for you....well there you go.

    Best luck finding the right boat, it's out there somewhere. Patience is your friend.
    Steve

    If you would have a good boat, be a good guy when you build her - honest, careful, patient, strong.
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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by stromborg View Post
    You need to build the boat that calls to you
    Absolutely. All that work for something which isn't inspirational...........doesn't bear thinking about.



    if some stodgy transom-sterned boat does that for you....well there you go.


    Best luck finding the right boat, it's out there somewhere. Patience is your friend.
    Thanks. And you're right. This build won't start for more than a year.

    Do you have another photo showing your bilge keels?

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    Default Re: Whisstock design #146: potential keel variations


    Just so we are using the same terminology: They are bilgeboards in that they pivot into and out of the hull like a centerboard, not fixed keels like say those found on a Westerly Centaur.

    The picture shows one deployed about as far as it comes out on the building frame, they will pivot to straight down if left to their own devices, I have found that keeping them deployed at about a 45 degree angle gives the best overall balance. The light colored rectangle behind the 'board is the roughly 400 pound (180kg) lead keel prior to getting a coat of bottom paint. The boards themselves weigh in at about 90 pounds (40kg) each, a pretty decent percentage of the overall ballast.
    Steve

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    H.A. Calahan

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    Default Re: Whisstock design #146: potential keel variations

    Brilliant, thanks.

    That is such a nice looking boat.
    Last edited by Mike-in-Suffolk; 09-03-2021 at 02:42 PM.

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    Default Re: Whisstock design #146: potential keel variations

    As long as you don't mind the pointy stern...
    Steve

    If you would have a good boat, be a good guy when you build her - honest, careful, patient, strong.
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    Default Re: Whisstock design #146: potential keel variations

    Seems to me that offsetting a centerboard trunk to be the seat riser can be a good compromise.
    Suggest this to your designer.

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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by JimConlin View Post
    Seems to me that offsetting a centerboard trunk to be the seat riser can be a good compromise.
    Suggest this to your designer.
    That's what he suggested to me. It's me that is somewhat uncomfortable with the idea. I was hoping someone here would say "terrible idea, because of X,Y & Z".

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    Default Re: Whisstock design #146: potential keel variations

    There’s considerable advantage to twin off center bilge boards besides the foot room like on the Eun Na Mara.

    1. Mud and stones don’t get pushed up into the slot so easily when the boat is dried out and resting down on the keel. Jammed centerboards can be a bit of a thing on boats that dry out.

    2. With twin boards you can if you want have assymetrical profiles and toe adjustments to improve efficiency. The board to leeward also can be canted out and naturally sits lower in the water improving grip as the boat heels compared to the same centerboard that looses efficency as it heels.

    3. Downwind you can deploy both to reduce rolling.

    4. You’ve always got a spare to sail on.

    5. The wash from an off center bilgeboard isn’t running over the rudder.

    6. The twin cases structurally reinforce the turn of the bilge, typically a contact point when dried out.

    The Eun Na Mara’s a great little boat. If you must you could strip one, otherwise Garside has several 16-20 ft strip planked transom dedigns in the model of Charles Stock’s boat that sailed the East Coast alot, have you read the books? You might be better to build the Whisstock as designed as twin off center bilge boards would impede access to the toilet and galley as drawn, though it might be re jigged. I had a bilge keeler once and it performed well, but i’d keep a small sub 20ft boat ultra shoal draft for easy mooring availability, easier launch/ recovery, less worry about touching the bottom up creeks and easier future resale. The ability to still drop an off bilge centerboard down to re antifoul it while the boat is on the trailer still, is a considerable one like in the picture above. If a centerboard gets jammed it can mean a boat yard lift to get under it enough and rake/ jet it out. Depends on your particular harbour mud/ stones though.
    Last edited by Edward Pearson; 09-04-2021 at 02:53 AM.

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    Default Re: Whisstock design #146: potential keel variations

    Well, I'm thinking fixed bilge keels, but if I went for bilge boards (liftable), it wouldn't make much difference to the internal layout as I am planning on doing away with the toilet anyway. I'd rather have a place to sit inside, so a stowable toilet unit under a saloon seat is my current thinking. But................thinks..........

    ........I'd only have top access under the seat if there was a trunk built into the face. I wouldn't want that everytime anyone wanted the Portaloo.

    Given how fixed bilge keels are absolutely everywhere here, and how our estuaries (where I'd do most of my sailing) have huge tidal ranges leaving scores of boats sitting on the mud for much of the time, can anyone think of an advantage of liftable boards over twin fixed bilge keels?

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    Default Re: Whisstock design #146: potential keel variations

    A boat that draws 3ft with bilge keels, will need a steep ramp, long trailer, non slippy ramp and quite a powerfull car, poss 4wd unless you want to pay for boat lift (usually 200). You’ll gave to launch/ retrieve at exactly right time. Immerse all the brakes in saltwater.... You’ll also not have such a wide window when your boat is afloat to get on and off your mooring if it dries out. You might want to get off at low to catch the flood tide to somewhere...Shallower moorings usually cheaper, but all depends on your river. I would also consider leeboards. Notiing in the boat. History of them with the Thames barges. Bilge keels are better for fatter boats that need more sail and more ballast. Thames estuary is notable for shifting sands and banks if you’re heading down there. I’d want to know i could skim over a bank or get off easily. You’ll have less concern with a shoal draft (big dinghy with a lid).

    Well designed bilge keelers can perform well, though the windward keel can sometimes pound and generally you’ve got a bit more drag. You’d have a load of structural work to do, and wouldn’t be cutting corners over shallow ground so much, you’d be thinking like a keelboat owner rather tgan a dinghy sailer.

    The centerboard top usually ends up as a seat, semi protected/ warm and with good viz at the center of pitch. Usually end up half in saloon and half in cockpit area. Has its uses dedpite the intrusion.
    Last edited by Edward Pearson; 09-04-2021 at 08:29 AM.

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    Default Re: Whisstock design #146: potential keel variations

    I don't usually comment on my designs on this or any other forum, as any builder or interested builder can get straightforward professional advice and information directly from me.

    However, as I have told Mike, the design can be modified for bilge keels, but that will increase the draft to at least 600mm and, with the best will in the world, the performance will suffer a bit because of the extra drag.

    The most efficient way to have a clear centre sole in the saloon is an offset centreboard – OK a bilgeboard. This could easily be accomplished on the port side, specially if Mike doesn't want a separate toilet compartment. The top of the centrecase (bilgeboardcase) is 300mm from the underside of the sole – which is almost perfect height for the underside of a seat. And most Portapotti type toilets are at least this height, considering that the base would have to be at least 100 above the sole to get sufficient area to park it. It can also be accomplished on the starboard side with some modifications to the galley.

    It's a little ironic that the whole reason to design #146 was to have a separate toilet compartment which the 'parent' design, #119 didn't have!! In this case, I would build #119 as she is specifically designed for a Portapotti type toilet installation.

    Both boats would be fine with a single offset bilgeboard incorporated in the furniture fronts. We've done this with #123, a larger version of #119. You don't really need twin bilgeboards as long as the single one is not too far from the centreline. And it's surprising how far from the centreline it can be and still function efficiently even when it's on the weather side.

    An alternative to a bilgeboard is an offset daggerboard. This has considerable advantages in that it occupies less space in the boat – and in the case of #146, could be incorporated in the front of the furniture unit forward of the toilet compartment, or the forward unit of the galley. The lift tackle would come out on the coachroof top and lead back to the cockpit. The only disadvantage is that it doesn't pivot up if you run aground – though we'd probably angle it at about 35, so it didn't catch weed, plastic bags etc etc.

    Cheers -- George
    Last edited by debenriver; 09-04-2021 at 11:24 AM.
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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by debenriver View Post
    ........It's a little ironic that the whole reason to design #146 was to have a separate toilet compartment which the 'parent' design, #119 didn't have!! In this case, I would build #119 as she is specifically designed for a Portapotti type toilet installation...........
    It was the extra foot of length which appealed to me the most, George, rather than the loo. As well as being an architect I'm a lifelong furniture maker and designer, so varying the interior arrangement isn't going to be any sort of issue. I was rather thinking I'd build the shell, ponder it with my wife, then take the measurements into Autocad and work out my own layout. Having 5.7m to play with rather than 5.35, at the cost of only 48kg, is the beauty of the #146 over the #119 to my mind.

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    Default Re: Whisstock design #146: potential keel variations

    Bilge keels, as opposed to retractable boards, are standard around here. I reckon they are possibly the most common keel type. Boats moored on our local rivers and estuaries are likely to end up sitting on the mud a couple of times a day, and staying upright is the huge advantage these keels give. So is it that these just aren't seen commonly around the world, or is it that bilge keels are a fibreglass thing, and rarely done on wooden boats?

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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by Mike-in-Suffolk View Post
    Bilge keels, as opposed to retractable boards, are standard around here..... So is it that these just aren't seen commonly around the world, or is it that bilge keels are a fibreglass thing, and rarely done on wooden boats?
    I've come across them now and then in my part of the world. Most moored boats here are in deeper waters, so they don't need to take the hard. The consensus seems to be that the sailing limitations outweigh the advantages of something that isn't strictly necessary in these waters. It has been some years since my friend had the one I last sailed on, but it was a 26 footer of wooden construction. I cant remember whether it was a Hartley or a Spencer, but she was a nice boat.
    There is nothing quite as permanent as a good temporary repair.

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    Default Re: Whisstock design #146: potential keel variations

    The late author/designer Maurice Griffiths drew a number of small bilge-keeled boats for the kind of estuary sailing enjoyed. The Eventide Owners Group (http://www.eventides.org.uk/) has some of his plans available but I think the boats are longer than your design brief allows for. I can't think of too many sub-18' boats with keels, much less bilgekeelers though that may have something to do with geography and tradition. We don't have the same history of mud-berth boat moorage you British sailors do. Seems like a very small niche indeed, it will be interesting to see what you come up with.
    Steve

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    Default Re: Whisstock design #146: potential keel variations

    Perhaps the most well known bilge-keeler is the Westerly Centaur 26 with over 2,400 being built. But this was a true bilge-keeler in that it didn't have a centre keel – just the ballasted bilge keels.

    What Mike is talking about is adding bilge keels to a boat with a centreline ballast keel – which is rather different, and presents different problems – not the least of which is the additional drag and the water flow between the three keels.

    We have done this once only on our Design No. 067 (30') and as far as I know the boat performed pretty well – I kind of lost touch with the builders/owners after they completed the boat and set off "round the world". I assume that if she were a 'dog' I would have heard from them!

    We, as a boatyard back in the day, built many Maurice Griffiths designs – but no bilge-keelers to his design (some to other designs).

    Having sailed the East Coast of England for many years – from birth onwards in fact – mostly on a 38' family ketch drawing 5' or so, we never really had any problems with draft. But it is true that if you wish to keep your boat near the top ends of the various tidal rivers, and not in a marina then bilge keels have their place. But I can't agree with Mike that they are "standard here" because that is not really the case.

    Cheers -- George
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    Default Re: Whisstock design #146: potential keel variations

    The Lysander 17 is another small bilge keeler, but no where as pretty as the two designs Mike has looked at. I had a Lysander for many years and was very happy with it. LOA | Lysander Owners Association

    If you are intending to sail on rivers as wall as the sea, then I would go for a design without the long centre keel, just bilge or twin boards will make for a much easier tacking boat.. Though of course needing slightly more attention in a straight line.

    Oh twin asymmetric boards give a huge advantage going to windward..
    Last edited by The Q; 09-06-2021 at 08:27 AM.
    Just an amateur bodging away..

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    Default Re: Whisstock design #146: potential keel variations

    You can add the Silhouette and the Debutante to the list of small bilge keelers. I think they are both Robert Tucker designs neither give anything close to sparkling performance.

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    Default Re: Whisstock design #146: potential keel variations

    I'll take a look at those, thanks. And yes, I would be using this on rivers and the Norfolk Broads, as well as on the coast.

    I have to say after thinking about it for a while that I think 3 keels is a sledgehammer to crack a nut, and I'd probably rather have on off centre centreboard.

    Quote Originally Posted by Hwyl View Post
    ......neither give anything close to sparkling performance.
    Sparkling performance isn't the top of my list of priorities. I'm too much a novice to need that.
    Last edited by Mike-in-Suffolk; 09-06-2021 at 10:19 AM.

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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by Mike-in-Suffolk View Post
    .
    Sparkling performance isn't the top of my list of priorities. I'm too much a novice to need that.
    The older designs being mentioned were not great to windward and ,while gentlemen don't beat to windward, saving a few extra tacks in confined waters is quite useful and that is what the better designs now available can do, even if looking a bit 'classic'.
    My little Oughtred faering, with nicely shaped foil board and rudder, easily outpointed most of the other assorted boats in the sail and oar group in the festival in Brittany.
    A2

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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by debenriver View Post
    ......... But I can't agree with Mike that they are "standard here" because that is not really the case......
    What I meant, but didn't say clearly, was that bilge keels (fixed) are standard in comparison with bilge boards (liftable). In other words, if you are to have a keel at the bilges, it is standard around here to have fixed keels rather than (retractable) boards in a casing. I don't think I've ever seen a boat with the latter, although, most times you see a boat you have no idea what is going on below the waterline.

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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by Mike-in-Suffolk View Post
    What I meant, but didn't say clearly, was that bilge keels (fixed) are standard in comparison with bilge boards (liftable). In other words, if you are to have a keel at the bilges, it is standard around here to have fixed keels rather than (retractable) boards in a casing. I don't think I've ever seen a boat with the latter, although, most times you see a boat you have no idea what is going on below the waterline.
    Google Fairey Atalanta..
    Twin drop bilge plates from the 50s. I recovered one from Sardinia in '69. I was young and lucky. It had been sunk and the engine US, but the weather smiled and we made it St Tropez where we hauled her and towed her to UK. Bit of an adventure back then..

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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by Mike-in-Suffolk
    Sparkling performance isn't the top of my list of priorities. I'm too much a novice to need that.

    I was being subtle. They are dogs.
    they don''t steer well in a breeze.

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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by Mike-in-Suffolk View Post
    Sparkling performance isn't the top of my list of priorities. I'm too much a novice to need that.
    Actually I think a novice needs "sparkling performance" much more that a seasoned sailor.

    An experienced sailor will be able to deal with a 'dog' and likely still not get into trouble as they will be able to understand and compensate for the shortcomings much better.

    Cheers -- George
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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by Andrew2 View Post
    Google Fairey Atalanta..
    Twin drop bilge plates from the 50s. I recovered one from Sardinia in '69. I was young and lucky. It had been sunk and the engine US, but the weather smiled and we made it St Tropez where we hauled her and towed her to UK. Bit of an adventure back then..
    Wow – I remember those – we had one or two based at the yard in Woodbridge. If I remember correctly the bilge plates occupied a huge amount of room in the interior?

    Cheers -- George
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    Default Re: Whisstock design #146: potential keel variations

    Quote Originally Posted by debenriver View Post
    Wow – I remember those – we had one or two based at the yard in Woodbridge. If I remember correctly the bilge plates occupied a huge amount of room in the interior?

    Cheers -- George
    Hi George
    Yes, they were long cast iron plates with screw lifting mechanisms and clamping brakes. Ours were a bit sticky.
    Still quite a few around as the hot moulding was quite durable, and enthusiastic owners to look after them. Bit quirky, but sailed well.
    Fairey also built the hull for George Stock's 'Shoal Waters'

    Back to Mike's musings on boards & plates
    Last edited by Andrew2; 09-07-2021 at 01:33 AM.

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    Default Re: Whisstock design #146: potential keel variations

    I had a quick look at Silhoutee and Debutante (Robert Tucker), and they're too mid-century in their styling for me, even if they could be rigged as gaffers. As they're apparently dogs, I'll move swiftly on.....

    Quote Originally Posted by Andrew2 View Post
    .....Back to Mike's musings on boards & plates
    No, no, I'll be musing on what to build for the next year, no doubt. The meanderings of conversations like this is one of the best things about forums, I reckon. The boat I would love to build is Atkins Maid of Endor. But it just doesn't fit my brief, and would be a nightmare to trail around. George's 146 is really pretty and would do exactly what I want it to do. Same with the Evening Swan....but she is so heavy.

    George, (or anyone else who knows), could you explain "Displacement on DWL", please? Anything floating displaces its weight, so all I can think is that displacement on DWL (Datum waterline) means displacement when the boat is loaded such that she floats to her DWL. That would mean, if I'm right, that to get to dry weight you would need to subtract whatever weight you loaded to bring her to DWL. Or if DWL is below the level at which she sits when empty it means that something has been left off the boat in calculating the displacement at DWL. I'd really like to be able to do a direct comparison of dry-weight to dry-weight.

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    Default Re: Whisstock design #146: potential keel variations

    Design water line is where it is expected to float when fully loaded for cruising. Dry weight? need to ask the designer or a builder. George does put dry weights for some of his designs. Expect he will be along shortly to comment.

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    Default Re: Whisstock design #146: potential keel variations

    Listen to the designer. This is his business and name.

    Now for my 2 cents.
    Your putting it on a trailer so fixed bilge keels have to be out. Too much hassle for a fun sail boat. (I have had a couple of trailer sailer's with 2'6" draft).
    Also that extra 1' of draft they cost will be important on a low tide or sandbar. 12" draft is way better than 24" or 30" when sneaking around up an estuary.

    Off set center boards are quite common in the size range you are looking at. A number of American. Designers use them. (I have issues with symmetry)
    Just 1 pivoting board up to say 12" off center.
    If you really have an issue then look at leeboards as suggested above.
    Z

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    Default Re: Whisstock design #146: potential keel variations

    DWL – datum Waterline – is usually the waterline the designer chooses to take as a datum line for heights – heights above often being positive and heights below being negative. It is also usually an early approximation of where the boat will float in sea water. Not all designers work this way, but many do.

    Displacement on DWL is exactly that – the weight of water the boat would displace floating on the DWL – and thus the weight of the boat at that point.

    LWL – load waterline is where the boat floats under different load conditions – gear aboard, or not, tanks empty or full, crew aboard or not, etc. etc. In practice the DWL is often about the same as the Lightship LWL – that is usually the weight of the structure, plus spars, sails etc., but no gear, crew, fuel, water etc.

    On larger yachts stability calculations are often done at 10% load and 100% load as being the two extremes that the vessel is likely to operate between.

    With Design #146 the calculated weight of the structures, rig, outboard, including the interior furniture, toilet, sink, cooker etc. is 718kg.

    The theoretical displacement floating on the dwl is 787kg – but actually it is more than that because the design is to the inside of the hull skin – the thickness of the hull below the dwl adds about another 55kg, so the working displacement to the dwl is about 840kg, depending on hull skin thickness.

    The stability curves for the boat are given floating 40mm deeper than the dwl - essentially the 100% LWL. Floating on that waterline the boat, to outside of a 9mm skin will displace (weigh) about 1100kg.

    Provided you keep your interior furniture light, as designed, and don't add lots of unnecessary structure etc. I think you could reckon on a dry trailer weight of about 700 - 750kg. A strip-planked and glassed hull will add a bit of weight over the ply lapstrake hull, as will a cold-moulded hull. The advantage of the cold-moulded hull is that, although it is a little thicker, timber being about half the density of sea water, the extra thickness of the underwater area also provides extra buoyancy.

    Cheers -- George
    To be truly free to live, one must be free to think and speak.

    A C Grayling

  34. #34
    Join Date
    Jun 2021
    Location
    Suffolk, UK
    Posts
    143

    Default Re: Whisstock design #146: potential keel variations

    Very useful, George. Thanks very much indeed.

    On that basis, if I were to be making a decision right now, I'd plump for the 146 over the Evening Swan, and build it in clinker with a single off-centre board. 720kg compared with C.1100kg for the Evening Swan (with adjustments for swapping an inboard for an outboard in a well)...well, that's huge. In fact, the ES is 50% heavier than #146. Trailer sailing, that is going to be a big deal, methinks. 20 sq m of sail for 1100 kg, too as opposed to 18 sq m (I won't be doing a mizzen) for 720kg.......1sq m pulling 55 kg for the ES, and 40kg for the #146. The power to weight ratio is firmly in #146's favour.

    George, there's not a lines drawing listed for the #146. I'd quite like to make a half model at some stage. What do people do?

  35. #35
    Join Date
    Aug 2010
    Location
    Rockland Maine USA and Woodbridge, Suffolk, England
    Posts
    566

    Default Re: Whisstock design #146: potential keel variations

    There's a small lines plan on the Design Data section https://www.whisstock.com/page_02.ph...6#open_modal10 but it's not really useful for building a scale model – just getting a general idea of the shape.

    If you tell me what scale you want to build the model at and, assuming you are making the model bread-&-butter fashion, what spacing you would like the waterlines at (i.e. the thickness of your waterplane slices), I can include a suitable lines plan in the design package, no problem. You can then print this out and prick through on to you waterplane slices. Or you can have it as a dxf file and open it in whatever CAD program you use. I can also provide a 3D IGES file of the surfaces, but this is probably less useful for model making – but maybe useful if you want to design your own interior furniture.

    Cheers -- George
    To be truly free to live, one must be free to think and speak.

    A C Grayling

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