Latest News: Forums Technical removable outboard bracket Re: Re: removable outboard bracket

#9852
Swiebertje
Participant

Exact measures cannot be given because there are several tank constructions. My old 1970’s MK2 needed four bolts inside the tank but with more recent boats the two top bolts end up in the gutter between the transom and the tank top. Because of this, the shoe sits higher on the transom then on the old boat. Some boats have a partially re-enforced transom and you can’t get as far away from the center line as you may wish.

Here is how I did it:
1. Make a paper or cardboard template in the shape of the shoe with markings for the holes.

2. Move it as far away from the center line as it will go, but first check for reinforcements in the transom. Keep it parallel to the rudder pintels (use the pintels as a reference).

3. If you think you are in the right location, dril a small (3mm) pilot hole in one of the two lower bolt positions. This will connect the inside and outside measurements.

4. Fit the template inside the tank so you get a pretty good idea where the holes will go.

The reason you need to use one of the lower bolt holes as a pilot is the upper holes may end up too close to, or in between the gutter and the tank where they are hard to repair. The lower holes are much easier to reach inside the tank and are much easier to fix if need be.

5. If the position wasn’t good, fix the pilot hole and drill a new one. Chances are the pilot hole will disappear behind the shoe and the backing plate and will be waterproofed by the Sikaflex. If not a 3 mm hole is easy to fix with some gel coat repair. Repeat from step 3.

6. Check that the bolts and nuts fit either in the tank or in the gutter and can be reached by a wrench.

7. The upper edge of the motor mount should be about the same height as the transom. Check there is sufficient space above the the bracket to mount the engine. Too low isn’t a problem, you can always use a higher motor mount but if the engine does not fit over the mount….

8. Test fit the baking plate, if any, in the tank. Note that some older models have a strong piece of plywood glassed in the transom voiding the need for a backing plate.

8. Once you are absolutely satisfied with the position of the holes, the plate and the shoe, drill the four holes using the template. For accuracy drill four 3 mm holes first, before drilling the final 8 mm bolt holes required by the B&B shoe. I drilled 10 mm holes to allow some play but more important, to allow the Sikaflex to get in the holes, next to the bolts.

9. Mount as Tempest51 described with lots of Sikaflex. Tighten after it has been allowed to set for a few days. Compressing the Sikaflex makes a better seal. Excess Sikaflex can be removed (or modeled in to shape) with paper towels and White Spirit, Toluene or Xylene thinner. Bring a roll of kitchen paper to have a good supply of fresh paper towels and wear rubber gloves.

Don’t bother to use an expensive piece of wood for the motor mount. When the motor ‘bites’ in to it you will find that it will get tatty real soon. The easiest approach is to replace it every so many years.
Use plywood for a plank will break along the grain due to the motor vibrations and the forces involved. On my boat I use two pieces of 18 mm ply, glued together to make a 36 mm thick motor mount.
I have made recesses for the motor’s wing bolts so the motor won’t come off easy if the bolts loosen due to the motor vibrations. Also they make a bolt lock more effective. If you lock the engine to the boat don’t forget the secure the bracket as well. For example by an eye on the transom and some SS-wire that goes on the same lock that locks the wing bolts.