John Spencer's designs

Discussion in 'Sailboats' started by Milan, May 20, 2005.

  1. Martin B.
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    Location: Mandurah, Western Australia

    Martin B. Junior Member

    + 1 for CT249's last post.
    My Scimitar 35' was built with full length stringers 2 piece laminated about 30 wide and 25 deep for the 2 glued pieces.
    The stringers sat outside the transverse frames ( not notched in) and the frames themselves were sawn straight timber with glued and nailed (or screwed ?) plywood gussets at the keel and chines. Like CT247's , the frames would have been something like 150 mm from inside of ply skin to top edge of frame and, yes the floors did stick up slightly thru the cabin sole out at the bunk fronts.

    As posted previously, my keel bolts came right thru the hog and frames to just under the cabin sole. MUCH deeper structure than shown in you pics above. Did not mention previously but the heavy steel plate which was the top of my fabricated hollow keel built fairly close to the original plans, had the top plate about 200 mm wide so there was a fairly generous transverse spacing in the keel bolts.
    "Soft" flexing hull bottom would not be a surprise to me on your craft with the shallow thin structural members shown in your pics above.

    Unfortunately I no longer have the beautiful "Matthew Flinders" and, despite lots of mods and improvements, I do not have any pics of the inside structure.

    See if you can locate any original plans of one of JS's designs - does not really matter which one and you should be able to get an idea of the great man's design and structural intent.
    You should be aware that John was a qualified Architect and whilst not a structural engineer, he did know what he was doing with plywood !
    Best of good fortune with you repairs/alterations.
     
  2. Monarols
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    Monarols New Member

  3. Oleboynow

    Oleboynow Previous Member

    crewed on Buccaneer sometimes in the Gulf, was always fun with Tom
    as you all know, Buc one the Syd Hobart one year
     
  4. Monarols
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    Monarols New Member

    Buccaneer

    I bet it was, I was a barman at Mansion House Kawau Island when Buccaneer sailed into the bay. The impact was the same as rolling up to the flyin in a Gulfstream V. Litweight, strong and fast, banned for years from the Sydney to Hobart it's reputation spread across the Pacific. Spencer's designs led the world. Not bad for a man who was told he would die at a young age.
     
  5. CT249
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    CT249 Senior Member

    Bucc wasn't banned from the Hobart; the CYC's rule on minimum skin thickness was withdrawn (or ignored) after it was proven to be silly so she was allowed in. I'm not sure to what extent the skin thickness rule prevented Ragtime/Infidel from doing the Hobart, as Clark and Spencer were adamant that refitting her for serious globe-trotting offshore work was impractical on other grounds.

    It's a pity Bucc didn't have a bigger rig and budget. I love the boat (and did a Sydney-Noumea on her) but although she was light, she was normally beaten by the heavier, bigger-rigged US maxis like Ondine II, Kialoa II and Passage. Towards the end of the IOR days I used to daydream about what she'd be like with a bigger fractional rig and new foils. She did get a mast extension when she was owned in Sydney, which may have helped her to win the Sydney to Rio race against a very small fleet including the 83' Anaconda II.
     
  6. GeoffinSouthOz
    Joined: Apr 2016
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    Location: Port Pirie, South Australia

    GeoffinSouthOz Junior Member

    Spencer Serendipity 28 (or 29 in SA for some reason)

    Saw the thread and decided to drop in. Negotiating for a Serendipity '29' which seems to be a '28' elsewhere. Giselle II is a GRP version of the Serendipity and according to her current owner, measures 28 and a half feet. She's at Wallaroo on the east side of Spencer Gulf at the moment and hasn't been sailed in some years. Would love to find her history if anyone knows her and plans if someone has a set. She was at Whyalla for some time and there was apparecntly an identical boat in the next berth.

    Geoff in South Oz
     

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  7. Jamie Kennedy
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    Jamie Kennedy Senior Member

  8. GeoffinSouthOz
    Joined: Apr 2016
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    Location: Port Pirie, South Australia

    GeoffinSouthOz Junior Member

    Ok, thanks for that. Knew a bit of that and his most notable designs such as Buccaneer, New World and Infidel/Ragtime. Still seem to be a few Serendipitys around, some ply some GRP. Probably 4-6 in SA waters (Mystic in Port Adelaide is currently up for sale in fact).

    Great designer, innovative and imaginative.

    Geoff
     
  9. CT249
    Joined: May 2003
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    CT249 Senior Member

    I have an old Modern Boating magazine test of the 'glass Serendipity, a copy of an ad for the British production run, two copies of the original small articles with the study plans, and a Serendipity of my own, and in all that there is no mention of the S28 being "stretched" to 28'6". I've had copies of official measurement certificates for three wooden ones that were measured for offshore racing and none of them is 28'6". It would be interesting to see if the extra six inches in the SA ones is real or not. One of the Yachting Victoria handicappers had a 'glass one, I think, and he measured it at 28'.

    I keep an eye out for information on Serendipitys and I've never heard of Giselle. I like the window surrounds though; I've been planning on doing something similar to mine to reduce the visual height of the coachroof sides. Are there any other pics?

    The 'glass boats tend to float fairly low compared to the original design and from the very small pic Giselle seems to have the same issue.

    I'm biased but I find them a great boat; easy to sail, compact but with all you need for weekending (IMHO). For racing they need fairly good sails and a keen, attentive crew; they are easy to sail but because they have small rigs and only moderate initial stability, they have to be well trimmed at all times.
     
  10. GeoffinSouthOz
    Joined: Apr 2016
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    Location: Port Pirie, South Australia

    GeoffinSouthOz Junior Member

    If you have scans of any or all of that I'd be very pleased to have a copy.
    The current owner was very definite about her being 'twenty eight and a half feet' so it's a bit of a mystery to me as well - and to others as well, not sure why only in SA either. Hopefully I might get to the bottom of it. I'm wondering if that rocket ship stern has something to do with it.

    She was in Whyalla 7 years ago (last haulout) and in Wallaroo ever since.
    Here are some more pics, the haulout pics are doubtless 7 years ago.
    I'll have more soon after I've done a prepurchase inspection.

    $_20.JPG

    $_21.JPG

    $_22.JPG

    $_75.JPG

    $_24.JPG

    $_23.JPG

    So I gather, they are a bit heavier apparently.

    I'm told they are easy enough to sail, but not easy to sail fast - hard to find the 'sweet spot' on the heel it seems and harder to keep on it. Go like a scalded cat downwind it seems with a decent blow behind them. We're mostly looking at weekend or 1-2 week cruising for 2-4, but might put her in the Tripolis next time around and maybe give some of the Trailer Sailers a surprise. Toying with some ideas about keel mods - seems the Scimitar is similar in that area - there's even one with a shortened keel with wings attached - as a former pilot might have a play at that and reducing her draught wouldn't hurt - it's really shallow around here at low water.

    I'll put up some more pics when I've been over her - and hopefully solve the '29' puzzle.

    Cheers

    Geoff
     
  11. Martin B.
    Joined: Aug 2013
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    Martin B. Junior Member

    Geoff, if you are thinking keel mods on your Spencer, then check the details in post 95, 97 etc above re the mods I made waaaay back in the mid 1970's on my Scimitar 35'.
    In hindsight a completely new keel as I discussed in the later post(s) using the original lead plus more to match the mass of steel would have yielded an even better result but remember, info like the actual profiles of NACA, was not available to the general sailing public like me at that time.
    The key to my keel improvement was the rounded leading edge to overcome the stalling and separation. The extra area added by the aft mod was probably not necessary; it was done for 2 reasons. Firstly to try to get the location of the maximum chord thickness from just aft on midpoint to further forward of the end result keel shape and, secondly, my consern for the integrity of the fabrication at the original trailing edge.

    If you reduce your draft from JS's original then you will need more lead to retain your righting moment - these magic light plywood chine boats need to be kept as upright as possible.

    Equally important was the replacement of the rudder with a deeper, thicker, foil shaped blade with heavier stronger tubular shaft considerably further aft.
    Wish I had never sold Matthew Flinders !
    Good luck with your craft.
     
  12. GeoffinSouthOz
    Joined: Apr 2016
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    Location: Port Pirie, South Australia

    GeoffinSouthOz Junior Member

    Yep, that's what I was looking at. I read them.

    As a former pilot it made sense to me, the original had what I would consider a critical leading edge, much like the F104 Starfighter (you could cut yourself on it) in short, high speed, low drag, but with a relatively shallow stalling angle of attack I'd say. Other factors too. So you could adjust that to make the 'wing' less critical and produce more 'lift' without too much effort. Some reshaping with a grinder and a MIG welder might be in order. And I live in a city with a lead smelter heh. So I'd certainly look at all that.
    It also occurred to me that you could fit retractable leading edge slats that would increase the lift on one side or the other depending on which side you deploy them - since the keel is a symmetrical aerofoil, you can't adjust the angle of attack to give more righting moment in the direction you need, but if you were to pop up slats on the lee side it would give more laminar flow and reduce stalling, with more 'lift' on that side without creating significant drag issues (more lift = more drag) on a run as they could be retracted for a downwind run. Not sure if that's practical - air is not water - but they are both fluids so....

    Don't disagree, but less critical to Giselle is she is all GRP not the lighter ply version or even GRP over ply. Several hundred kg heavier as I understand it. Not sure how that will affect her yet. My understanding is that the ply boat was lighter, faster and rather touchier, the plastic ones like Giselle are more of a plodder but not quite so critical - but the overall design is still good so plenty to work with, I don't think much consideration for this was inherent in the shift from ply to GRP hull, though there's still that as yet unexplained 29' business here - the current owner is quite definite she is '28 and a half feet' long, so I'm hoping he has some paperwork somewhere so we can finally solve this one.

    I'll look at that as well. Not my boat yet, but hoping. Crawl through inspection probably this weekend, then we'll hopefully make a deal.

    Whatever became of yours? Don't think I've heard of her around here at all?

    Cheers
    Geoff
     
  13. CT249
    Joined: May 2003
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    CT249 Senior Member

    That looks like the standard interior layout, which mine has and which seems to work really well IMHO. We've had four adults for a week or so and three adults and three dogs for 4-5 days, and it all worked well.

    I agree about the keel section mods; I've been meaning to do it to mine for eons but we've barely raced her for (gulp) 15 years because of our cat, dinghy and windsurfer racing. The keel section is definitely too critical.

    When I was kid we had a light version of the 'glass boat, which had done JOG and a Brisbane-Gladstone before we got it. We weren't the greatest sailors and spent most of our time playing with the quarter tonners because of our lack of pointing - always an issue with that keel and the wide spreaders and chainplates. When I got into my early 20s I started looking for a cheap Serendipity to modify, because the basic boat has a lot of potential.

    My boat now carries an Etchell mast and main and a spade rudder off a JOG boat. She appears to be built to plan out of nice Bruynzeel ply and even before the diesel was taken out she was floating to her lines. The timber quarter berths have been replaced by pipe cots (not so much for weight, but because the space under the quarter berths is hard to get to for storage; it's easier to rotate the pipe cots to get into that area). With the fairly light displacement and narrow stern, the Serendipity seems very sensitive to keeping weight out of the back end. The info I have is that much of the extra weight in the 'glass boats is in the fitout and in the 1" thick 'glass around the bilges; obviously the latter is probably not too bad.

    The 150% headsail is a bit of an issue as far as I can make out. If you have a low clew, it's hard to get it over the high cabin top when tacking (although that was when we had dacron sails) and yet if you give it a high clew you end up running out of sheeting space aft. The good standard Serendipities (or lightly modified 'glass boats) seem to be about Sonata 8/Seaway 25 pace. Koa Atea (the original 'glass boat) went to Victoria where she had some minor modifications and (along with another modified 'glass S28) was rated at Sonata/Seaway/Thunderbird pace. Now under her current ownership she has dropped back a long way off that pace, as often happens with Serendipities.

    Once the new rudder went onto my boat she became similar in speed to the Peterson 30s; it's a very deep rudder and she goes upwind on it as much as she does on the keel. As Martin says, a new rudder can be a very valuable upgrade, and personally it seems worthwhile just because balanced spades feel so much better than skeg hung rudders.

    I'll do some scanning over the next few days if I can remember to find the photocopies or mags.

    They are a lovely boat. Mine is very scruffy indeed and logically we should just chuck her and go out buy something shiny, but it's just such a sweet little boat with so many memories, and in many ways so easy to own. The loads are incredibly light, the costs are low, and the handling qualities are excellent. I get the feeling you're one of the guys who will be able to get the Serendipity to perform to her potential.
     
  14. GeoffinSouthOz
    Joined: Apr 2016
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    Location: Port Pirie, South Australia

    GeoffinSouthOz Junior Member

    If we get her the Admiral will want some mods. Proper toilet in a compartment and a shower - may settle for a deck shower - but that would go just abaft the existing v berth bulkhead - not hard. Adds a bit of weight but will find a way to lose some aft perhaps.

    No argument, high speed wing = low lift/low drag so it's enough to keep her from turning over (just) but minimal drag on her best point (running before a howling gale). Given the glass boats like Giselle are heavier anyway which reduces their downwind speed a bit already, some keel mods could claw some of that back on points of sail closer to the wind (and improve her pointing which by all accounts in these is nothing to write home about) simply by making the keel less critical and produce more 'lift' for righting without increasing the drag on downwind legs too much. (Toying with idea of deployable - maybe automatic - leading edge slats or even trailing edge fowler style flaps to help with that) - lots of possibilities. Not seen engineering drawings of the keel, but I think some angle grinding and MIG reshaping might be in order.

    I've been told they don't point that well, again, making the keel work for a living could only help with that. And yes, the boat has potential, I don't think a lot of thought went in to compensating for the extra weight of the all GRP rendering of these, the extra weight makes it realistically rather a different boat to the all ply low displacement flyer.


    The latter is likely somewhat in response to the issue some ply S28s had with 'wobbly' keels due to a lack of strength in that area - to my knowledge none of the all glass boats have had this issue - so yes, good I think.

    Minimal race experience - bugger all for boats like that around here except the annual Tripolis (Pirie-Whyalla-Port Augusta) but might put her in that - at worst she'd scare some RL28/34 Trailer Sailer types on any downwind leg.

    The keel/rudder combination can be critical, particularly if the keel isn't performing well (and the stock one seems to have major issues) so a better rudder arrangement can help a lot. That said, if you get the bloody keel to come out of a stall for long enough to keep her closer to upright it will also reduce leeway dramatically, which might make the rudder less critical.
    Contemplating thickening the keel chord, rounding the leading edge and possibly shortening it with a couple of 'wings' at the keel tip to get some more righting moment that is proportional to the flow speed over them, getting the Angle of Attack right would be tricky, but it occurs to me that they could be adjustable 'in flight' so you could control the amount of force and in which direction it's going depending on point of sail etc. Interesting perhaps?

    That would be great, any engineering type drawings, particularly of the keel would be of interest, I can feed them to Solidworks or something similar and perhaps do some flow simulations. I feel sure the keel is the key and that these keels were optimised for minimal drag on a run at the expense of pointing and heel stability. I feel sure even a rank amateur could do some good here with a bit of thought - and maybe some lead in judicious places - Port Pirie makes lead by the kilotonne so....

    I like her looks, seems modern enough despite her age. Aside from lack of performance, particularly close to the wind, owners don't seem to have much to say about them that is derogatory - and I think the performance issues can be improved somewhat.

    I hope we end up with her - it will be a lot of fun.

    Geoff
     

  15. Phil Christieso
    Joined: Jun 2016
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    Phil Christieso Junior Member

    Athol Burns trained John Spencer
     
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