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  • #9057
    Algol
    Member

    @tempest51 wrote:

    Can anyone tell from the images if the jammer is the high or the low base Harken that is available?

    It’s the low base

    #9058
    Algol
    Member

    @Swiebertje wrote:

    1. To hold up the sheet in the middle an expensive block can be avoided by adding a piece of sail cloth from side to side or by a 4″ long piece of 1″ garden hose, tapered at the ends similar to your spi-pole drain pipes.

    As you’ll see in the picture, I’ve got a loop of 8mm rope hanging to stop the mainsheet dropping. I’m still not convinced it won’t take my head off at some point tho. Are there any alternative methods for this?

    Anyway, this morning headed out in a Force 5 and I lost my kicker before we went over the start line when a snap shackle, err, snapped 😳

    #9062
    Swiebertje
    Participant

    @bigal wrote:

    ……. but surely the whole point of having a boat is to put expensive gear on it – and in the UK the expenditure serves to reduce the inheritance tax liability in due course!! Think ahead !!

    Definition of a boat: A big hole in the water to throw your money in. 😉

    #9063
    Swiebertje
    Participant

    @Algol wrote:

    @Swiebertje wrote:

    1. To hold up the sheet in the middle an expensive block can be avoided by adding a piece of sail cloth from side to side or by a 4″ long piece of 1″ garden hose, tapered at the ends similar to your spi-pole drain pipes.

    As you’ll see in the picture, I’ve got a loop of 8mm rope hanging to stop the mainsheet dropping. I’m still not convinced it won’t take my head off at some point tho. Are there any alternative methods for this?

    Anyway, this morning headed out in a Force 5 and I lost my kicker before we went over the start line when a snap shackle, err, snapped 😳

    I saw the guide rope in the picture but the halyard is still pretty far below the boom. I believe that that piece of rope may jam the sheet some day, when you least expect it. I prefer a solution with piece of 1″ garden hose. Most of us have the sheet guide near where our head would be in a tack or gibe. This minimizes the chance of hanging yourself, but at the same time it maximizes the chance of being hit by a guide block. Trust me, garden hose is much softer on the head then a block. 😀 BTW, this is a location where there is more sheet between the guide and the clew then there is between the guide and the center block, but who cares as long as it is out of the way where it matters.

    To bad that your snap shackle snapped (isn’t that what a snap shackle is supposed to do? :mrgreen: ). Anyway, snap shackles are not very strong things. Suppose you are pulling 20kg on a 1:16 kicker. That means the kicker has 320 kg on it. I would look for a shackle that can handle at least 500kg.

    IMHO it is better is to use D-shackles or if you want it to be easy to remove, a pelican hook. In this thread is a picture of the Wichard pelican hook I use: http://wayfarer.org.uk/forum/viewtopic.php?f=4&t=508&p=2850&hilit=wichard#p2850 It is rated for 1280kg (breaking load 3000kg). This theoretically allows me to crank it up to 80kg. There is no way that I can pull that hard but we have to account for gusts that temporary increase the tension on the kicker. That is why it is more then two times stronger then the calculated 500kg. See page 32 of the Wichard catalog for strength data here (6.5MB PDF Allert!): http://www.wichard.com/documents/stainlessSteel.pdf

    #9136

    How do you know what angle on the bottom of the wooden base ( that supports the partchet block) to cut ❓

    #9137
    Algol
    Member

    I used a folded piece of A4 as a paper template of the side view of the block and folded and refolded the bottom to suit the sloping c/b case until it looked like it’d give me a top surface more or less level with the thwart. Then I took that home and made a drawing which I took to the timber merchant.

    #9139
    Swiebertje
    Participant

    Here is how I did it:

    Measure the slope, using a square angle (tool), relative to the floor boards. Take two height values a known distance apart (E.G. a foot apart). With these three measures the angle is easy to reproduce on a piece of paper. Then copy the angle from the paper to a sliding bevel (tool) and transfer it on to the wood. Before you start cutting, compare the sliding bevel one more time with the aft slope of the CB case, just to be sure.

    If you don’t have these carpenter tools available, you can also cut the paper with a pair of sizers and use the paper as a stencil on the wood, similar to Algol’s method.

    #9142
    Colin Parkstone
    Participant

    What can also look good is to mark the base of the jammer on the top surface, ie a circle.
    Then plane or file with a rasp the block from the square base to the top circle.
    Looks rather nice I think!

    C P 😉

    #11540
    SeaHolly
    Member

    As a follow up to this thread, I am after some further thoughts on blocks to use on the boom and attached to the bridle.

    I have a nice Harken hexaratchet, attached to the Harken low jammer base, but don’t really want to spend a further £80 on three Harken further blocks.

    If I am using an 8mm mainsheet, can anyone suggest some sufficiently strong, budget or mid-range blocks that I could use to finish my conversion?

    Thanks,

    #11555
    admin
    Member

    Cheap solution I have seen is a couple of nylon rings about 25mm diameter through lacing eyes screwed to the underside of the boom. Two of those can’t cost more than a tenner and probably a lot less.

    I wish I had done that, but I used a short length of 50mm toe strap fixed with a st/st plate screwed on both sides of the boom. Heavier and a bit more expensive than those nylon rings.

    As you have discovered no doubt, unless the sheet is kept close to the boom it catches on your buoyancy aid behind you neck, so cheap means it hardly costs more to put three as two.

    #11556
    SeaHolly
    Member

    Thanks for the advice Mike, I had thought of a few webbing straps hung across the boom, but the nylon eyes are are a useful thought.

    What I am mostly looking for advice on is the actual blocks to us on the bridle and the two boom fixing positions. I have seen various Barton, RWO and other brand plain bearing blocks that seem to fit the bill for use under mainsheet tension. These blocks come in at a third or less than comparable 30mm Harken balbearing blocks.

    Racing performance is not critical to me – I do club handicap racing for fun, but don’t want to fork out unneccesarily for blocks that will make very little performacne difference.

    #11557
    Swiebertje
    Participant

    It does not matter if you are racing or not, you want the main sheet to run smooth with little friction so you have a good “feel” from the main.
    That is something any sailor likes. So treat yourself to a set of ball bearing blocks, you only need two single blocks anyway.
    Make the right choice and enjoy smooth sailing for many years instead of the aggravation of lots of friction or worse, seized up blocks.
    Even Harken 082-s go for about a Tenner each.

    Stay away from Barton. From my own experience I can tell that the plain bearings will jam in time.
    In my frustration I gave them free flying and swimming lessons and bought a set of ball bearing blocks.
    I guess you get what you pay for.
    I now have Ronstan 30mm ball baring blocks but the ones from RWO look fine too.

    BTW, Harken may be expensive here but if you have friends in the US or Canada…. Toronto….. Worlds…..
    Over there Harken is even less expensive then the well known UK brands over here.

    Another good and not very expensive brand is Sprenger, the only down side is that it’s not made in Britain……

    #11563
    SeaHolly
    Member

    Thanks Swiebertje, I found 082 bullet blocks for around a tenner each, so brought those, and am now ready for the conversion.

    Will post some pictures once the job is completed.

    Happy sailing!

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