Latest News: Forums Technical Outboard Bracket

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Viewing 14 posts - 16 through 29 (of 29 total)
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  • #7686
    tempest51
    Member

    Thanks Overdraught1, I use an outboard only occasionally and just use ply pads, which are adequate, after all we’re not talking about Dunkerque here. Maybe the Right Honourable Swiebertje could think about bottling some of that arrogance as I get the impression that it is much stronger than my Wessex System G5 resin and hardener, which bonds anything to everything.

    #7687
    BluTak
    Participant

    Tempest 51 – as a new member I am reminded of an incident in the office when a Dutch coleague was rude to a customer. My boss rang the customer and simply explained “Gerit isn’t rude – he’s Dutch!!!!”
    Incidentally you can get quite a reasonable bond with epoxy, aluminium and steel if you sand it first with wet and dry paper soaked in resin to abrade the surface and keep it from oxidising. Or my tiller extension would have fallen off years ago!

    Overdraught don’t go vandalising your boat yet – I will explain all tomorrow

    Swiebertje we have a saying in England that “there are more ways to kill a cat other than by drowning it”

    #7688
    Swiebertje
    Participant

    Hey guys, it is not my intention to be rude, my apologies to anyone that feels offended. It is not the epoxy per se, but self threaders I can’t see as a solution. We are talking about this bracket aren’t we?

    #7692
    BluTak
    Participant

    Here is how I did it. The ply pad is approx 7″ x 7″ and centred 10″ from the boat centrline on port side. I am right handed.

    The pad is made up of 9mm and 6mm ply – the 6mm ply goes to the transom top and the 9mm packing underneath the transom lip to make it flush

    The 6mm ply is drilled to take the shoe so that the shoe top sits approx 5mm below the transom top (the top two holes are about 30mm down). The transom is drilled right through for the top bolts which are clear of the tank. Slide the 9mm packing ply under and mark for lower bolts.
    Make 2 clearance holes in the 9mm ply to take the lower 2 nuts and large washers. You can now cut the bolts to length and dry assemble it.

    epoxy the pads to the boat with the shoe attached. Use the top bolts and a small self tapper at the bottom to clamp it. Sand and scratch the gell thoroughly to get a good epoxy key. fill the small tapper hole

    You need a backing plate (3mm stainless fine) for top bolts
    Use nylock nuts (locking)
    Use high grade ply or tufnol for top 6mm pad (or make it thicker). Robbins Timber “super elite” is suitable – you may get an A4 sample! “elite” is a bit soft
    When you epoxy use coloidal silica and don’t clamp too tight to avoid resin starvation
    Coat all the ply with epoxy/paint/varnish
    Use sealant under shoe and backing plate
    Make sure bolt heads flush in shoe so you can slide bracket on!
    If you grease the threads you can epoxy the washers/nuts in and should be able to take it apart. degrease the washers/nuts well and they should hold tight if you fill the clearance holes with thickened epoxy/silica when you fasten it all together

    While you’re at it two 1/2″ holes through top of transom with inserts are very useful for mooring or attaching a bridle if the mainsheet track pulls off. It happened to me! One hole can be through the shoe.

    If you send your address I can send you a sketch if its not clear. This is only one of many methods to fix the bracket and it works fine for me. No need to scrat around inside the tank! My engine (seagull shortshaft) is correct height and the rudder works fine. I put one on a friends with 15hp and he’s had no problems

    #7698
    Anonymous
    Inactive

    Hi Blu Tak – would it be possible to include a picture or two?
    Thanks
    Jon

    #7745
    BluTak
    Participant

    JonW – I’ve done a pdf sketch of it so if you email me or send your address I’ll send you a copy. my email is “timer_blair3@hotmail.co.uk”
    Robert (01539 729710)

    #7752
    BluTak
    Participant

    IMPORTANT (if you use my pad design for outboard bracket) The short shaft engines, both seagull and modern, are designed to work with transom depth of around 15″. This means that when you put on a bracket the top of the pad (to fasten the engine to) should be roughly the same height as the transom. When fitted as per my drawing/description you cannot have any of the plywood extending above the part of the bracket that the engine fastens to or the engine will be too high
    I use a fixed mounting that bolts to the pad (no thumbscrews) so that the engine is the same height as it would have been on the transom.
    If you too use a seagull you could buy a similar bracket (though they are rare) or modify the normal mounting by taking off the thumbscrews and bolting on your existing mounting
    If you use a modern engine and you need to extend the height of the plywood pad to get the engine on you could alter the rake of the extension bar to get the engine level. A welding/fabrication shop would do this cheaply and it will work just as well horizontal of even pointing down. You can get the engine height exactly right

    If anyone is confused please contact me and I will telephone you to explain.
    Robert

    #7753
    matoi
    Member

    My boat came with the same bracket as in Swiebertje’s photo and with a pad installed like this:

    When I looked how my Grandma’s 1974. Johnson engine would fit, I became suspicios that it would sit too high, so with some help from my father, modified the bracket. Here is how it looks now:

    Now, I find the height of the engine perfect – when the engine runs two people can sit around the centre of the boat without the propeler getting out of the water (at least in relatively calm water). The bastardized bracket is not completely perfect as it sometimes catches a bit of water with it’s lower corner. I suppose it doesn’t affect the boat speed, but it is at least philosophically problematic…

    Do you think my modifications would not have been necessary if I had a newer engine?

    Thanks.

    Mato

    #7829
    BluTak
    Participant

    I contacted boats n bits and they will sell just the bracket bit that fits on the boat for “around £20”

    So you can get the other bit made in a welding shop and vary the angle of dangle to suit your outboard length (and probably save money)

    The tapered plate on mine is 3.2mm thick (1/8″). 3mm would probably be fine. The length is 6 1/16″. The width top is 4 5/8″. The width bottom is 3 3/8″. There is a tapped hole to take a 6mm bolt with wing nut approx 1″ up from the bottom at the centre. Check this on your actual bracket. Round the corners and edges.

    The length of the arm is 8″. of 2 1/4″ x 2″ channel 1/8″ thick but box section, pipe or whatever would be fine

    I hope this is clear and will suit everyone. Apologies for delay my computer has been down. Any queries please contact me

    The plate at the other end should be suitable for mounting your plywood mounting (approx 1 1/2″ thick)

    #8006

    Just revisiting this thread having decided to go for the removable bracket option. Taking out the foam but was an quick easy job and I’ll take Swiebertje’s advice of putting something different back in.

    Next question is what to do for a backing pad. There’s what I assume to be a ply pad laminated into the transom which extends out about 300mm from the centre line. At the recommended 400mm I would be going only through the grp so obviously some substantial backing pad is required. What thickness ply is recommended? Presumably the bigger the pad that can be fitted in the better? Is it advisable to glass/epoxy it to the inside of the transom or is marine sealant sufficient?

    Any help much appreciated.

    Jonathan
    W2312

    #8009
    Bob Harland
    Participant

    I have always expoxied backing pads in position. I think if you used sealant it would probably be as good, but I am not sure there is any benefit.
    Sealant is used as a non-permanent bedding material – e.g. under fittings – I don’t think that applies here.

    I would say 3/8″ marine ply was about right and I would try to put as bigger peice in as I could. Perhaps that’s overkill – but I like to have confidence in my boat.

    Blutak describes the plywood he used above.

    #8010

    Bob

    Thanks for your comments, just need to pluck up the courage to start drilling …

    Jonathan
    W2312

    #8228

    To conclude the above communication, I thought it might be helpful to explain what I actually did in respect of the engine mounting.

    Since I also had to put on new rudder fitments and repair old screw holes in the transom, I eventually simply cut out the foam buoyancy blocks in the aft tank (no problem), thereby giving easy access to the inside of the tank and the back of the transom.

    I then sanded off the loose and flaking material in the tank before making a flat removable sole board and Flowcoating throughout, after filling the old holes in the transom. Thereafter I sanded down the transom, made wooden backing plates for the inside of the transom, drilled for bolts for both the engine mount and the new rudder fitments, undercoated with Blakes 2-part epoxy and top-coated with 5 coats of their Polygloss. We then smoothed off with Wet and Dry before polishing with G3 paste. Incidentally, I used a contrasting colour (dark blue) to the rest of the hull since I was advised it would be impossible to match the existing white on the hull. I then bolted on the various fittings and backing plates and used a liberal helping of Sikaflex to avoid water ingress. Finally, I installed a large buoyancy bag in the back of the aft tank.

    I am very happy with the end result. The task itself was not unduly onerous (I am not an engineer) or costly – once I had decided what to do and commenced the work. My biggest headache was in deciding how to approach the task and I am grateful for the various options and advice from members of the Association.

    Mike Norris

    #8239
    BluTak
    Participant

    Hi – it sounds like you’re well sorted! Re buoyancy bag beware shards of glass fibre from the hull puncturing it! I put one in the front of mine and it was punctured very easily. In the back I use close cell foam blocks and in the front since had it filled with foam recommended by a specialist as closed cell. With the blocks in the back I surrounded them with a ply box in which I store the outboard and a can of fuel
    Hope your’e sailing – I’m busy soundproofing a friends flat ceiling in this glorious weather! Robert

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