Latest News: Forums Technical Engine Mounting Bracket

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  • #4116

    I know there have been many postings on the forum regarding engine moiunting brackets etc – but please bear with me.

    I have a MKII with a ply engine mounting plate on the port side of the transom. I believe this is a common feature of many MKII’s and may even come as standard. Due to the problems with positioning of the engine at this location , which have been described many time on this forum, I have mow purchased a Boats ‘n Bits engine bracket.

    The problem that I have is that the fitting instructions for the mounting bracket ( 130mm down from the transom and 400mm port side the the centre line running through the rudder pintles) does not align it with the ply mounting plate. It seems to me that I have two options:

    1, Remove ply mounting plate and position mouting bracket as per instructions
    2. Ignore instructions and mount the engine bracket on the ply plate

    I would prefer Option 2 as it seems to me that removeing the ply plate would create more work and more damage to the boat.

    I accept that the engine would sit slightly higher in the water ( say 30 – 40 mm) – but I don’t think that would have an appreciable effect on performance, and also the prop would sit a little closer to the rudder – I could live with this if I remember to raise the rudder when engine being used.

    I would appreciate any observations from the more well informed of you who have already been through this for anything that I may have missed?

    #9010
    Swiebertje
    Participant

    I assume that you are referring to the ply board that is laminated in to the transom? Or are you referring to a separate piece of ply that is added against and/or on top of the transom? The latter has been added by a former owner and is not a standard piece of a Wayfarer. Get rid of it. You need to spread the load by adding (or using existing) ply *inside* the tank.

    The piece of ply that is laminated into the transom is symmetrical along the middle of the boat, on both sides of the rudder pintels. You can’t see it from the outside but if you stick your head in the tank you should see the thick areas in the GRP where the plywood is. Though the laminated piece of ply is not intended for motor support but to strengthen the transom for the rudder we can use it as such. The width of the ply piece varies because the builder did not have an engine in mind when he put it in.

    Just put the engine bracket as far out as possible, but make sure all four bolt holes go through the laminated ply piece (the one laminated into the transom). If for some odd reason that gives a bracket position too close to the rudder, you may need to add some additional ply to the inside of the buoyancy tank, next to the laminated piece that is already there. In this case two of the bolt holes go through the laminated ply and two through the additional piece. Under no circumstance try to remove or replace the laminated plywood. That is a major repair and would, at the very best make your boat subject to re-measurement. In the unlikely case that your boat has a very small piece of plywood laminated into the transom, you could use a full size plywood counter plate for all bolt holes.

    The height of the shoe isn’t critical because you can adjust the height if the engine mount plate. If the top of engine mount plate is about level with the transom it is OK. In my case the holes in the engine mount were not drilled and positioning it at the right height was easy.

    I have also seen boats with the engine mount fastened off center to bring the engine further out. This too may help positioning the engine when a boat has a small piece of ply laminated into the transom. (off center relative to the bracket obviously).

    The engine position isn’t that critical at all. You just want it far enough to the side where it won’t ‘bite’ the rudder, and deep enough to keep it submerged in a chop. But don’t put it too low, that may make it impossible to tilt it forward (to lift the engine out of the water while sailing). Either the transom is in the way of the engine head, or the screw drags through the water all the time. In my experience having the top of the engine mount level or slightly higher then the transom is a good position. It is not a matter of hundredths of an inch, just have it about right, give or take an inch.

    And don’t forget: measure twice, drill once.

    #9016
    Smillie
    Member

    Buttercup,

    You don’t seem to say whether you have a wooden or GRP Mk II, or whether the ply mounting plate is on the inside or outside of the transom. I don’t know the details of the Boats n’Bits bracket you have, but I fitted one with a fixed pad which takes a removable cantilevered section with an engine mounting pad on the end. The cantilever takes the mounting pad to about a foot behind the transom.

    My boat is a GRP Mk II. The wooden transom pad was laminated into the transom by the builder and can be seen from the inside of the buoyancy tank.

    Swiebertje is right in saying: keep it away from the rudder; get the vertical position on the transom so that you can tilt the engine up when not in use; make sure you have enough submergence when in use. I don’t agree that position isn’t that critical. When I did it, it took a fair degree of measuring to meet these criteria. As I recall, there were only a few square inches that were viable for the first hole to be drilled. I wrote a note about it at the time, but my only real innovation was to use a high power electric torch to shine from inside to outside to show the location of the pad in the glass fibre transom.

    It might be worth a practice run with a piece of board mounted in a vice or a Workmate to simulate the transom.

    David Smillie W5308

    #9030

    David and Swiebertje

    Many thanks for your helpful comments.

    I think I now have the way forward. Before I start drilling – I would like to check one further thing with you. The engine I propose to hang on the bracket is a 4hp 2 Stroke Yamaha – 19Kgs. DO you think this will be too heavy for the bracket attachment? ie: Will it rip out the stern end??!!!

    Many thanks once again.

    #9034
    Swiebertje
    Participant

    http://www.wayfarer-international.org/WIT/cruise.daysail/motors/motor_matters_index.html
    http://wayfarer.org.uk/forum/viewtopic.php?p=5190#p3648
    To name just a few, there is much more information available on motor matters but I am sure you can use this forum’s search options or browse through WIT without my help.

    #9046
    Smillie
    Member

    Buttercup,

    I’ve just weighed my Evinrude 4hp 2-stroke and was surprised to find it is about 18kg. It’s probably very similar to yours. I’ve had no problems with the transom, but it may explain one or two with my back! Best of luck and don’t rush the drilling – many of the people who tell you it’s a one hour job are remembering the second time they did it, or forgetting the measuring/thinking time for the first. I reckon it took me a couple of evenings measuring and marking up before I was sure enough to drill. By the way, you need to make sure that your holes are sealed to prevent leakage of air from what is a buoyancy compartment. I think I used a general purpose silicone sealant.

    Regards,
    David Smillie

    #9049
    Swiebertje
    Participant

    Never, never, never, never, never use silicone sh*t on a boat, not for any reason. Full stop. Period. Exclamation mark.
    And if you still feel you should, read the line above again.

    Use MS (PU) polymer instead (e.g. Sikaflex). This product stays flexible for many years, even when exposed to UV, bonds very well to GRP and metal and can be painted over. All characteristics that silicones have not.

    #9059

    Hello All

    Just a quick update on my little project. Bracket is now fitted and engine has been mounted and all appears well – next stage get out on the water and see what happens.

    Many thanks to all of you for your comments and helpful advice – it was very reassuring for me.

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