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Trim Tabs to an Eventide!??

 

 

When I re-launched Fiddlers Green in the spring of  2008 she had an odd appendage on her transom, see left.

I had been toying with this idea for several years and had just not got round to doing it, time and all that.  This year, as there was precious little to do at fit out time, there was no excuse.

 

 

     
 

Why fit them?

Well for years I had noted that with 2 or 3 people in the cockpit, at full throttle FG squatted her transom enough to get the helmsman's feet wet, by the water rising up the transom drain.  The drains are above the static waterline and the cockpit floor is 6" plus above the static waterline.  However when all the horses are unleashed from the Beta 17 then the water can rise halfway up the transom, seemingly.  Certainly I have a tide mark 9" up sometimes.

So I thought, what if I widened the transom, to give more lift....daft idea...!

 

The alternative was a pair of foam wedges glued to the underside.  If I used closed cell foam it would have a very slight buoyant effect, very slight, about 20lb!  however closed cell would not get waterlogged and could be easily shaped.

 

     
 

I chose to use builders insulating foam slab.  If I cut out several bits and glued them on top of one another I could carve them with a knife.... cost about 10.00 for a small slab.  I made them about 3" deep at the aft end and to fit from the WL each side down to the flat section of the underside of the hog.

They had to be a matched pair, so were glued together with epoxy, filled and faired, sanded and further epoxy coated, till I was sure they were as good as identical.

 

     
 

I also figured that if I stuck it to the underside of the transom with Sika-Flex, I could easily cut them off if it was a disaster, with a sharp knife.

to hold them in place for long enough for the Sika-Flex to set, I used  brooms and sticks with  ply wood packing pieces to spread the load and not crack the epoxy on the foam.  This was tricky, as if you did not get the support in the correct place, they gently slid!  Messy too, Sika-Flex is very sticky stuff!

 

     
 

As you can see it was simple enough.  I waited with the boat to make sure they did not slide when I turned my back though!
     
 

Whilst I was waiting I made myself useful by polishing the prop!  I always polish it up and for the last two years have coated it in Lanolin after I have finished.  This appears to lessen the amount of limescale deposit, and what was there after the previous year, came off easily.  I never have a barnacle on the prop. Last year there was a giddy one on the end of the prop nut!  How do they hang on there!
     
 

Chocks away and the wedge is glued in place!  You can just make out the two layers of foam.  Note the edge nearest the camera is still under the WL.
     
 

There was a  gap between the two wedges and I decided to part fill it with a thinner wedge.  The rudder has a leading edge that slots into this area, so I could not make it the full depth.  I trimmed a bit of foam on site to fit, then coated it with epoxy and it just held itself in place with Sika-Flex.
     
 

Here you can see the thinner wedge in the centre, above the leading edge of the rudder.  When all was in place I then went all the round with Sika-Flex filling all the edge voids and fairing off.
     
 

Looks a bit messy, but in fact it was as smooth as a babies bum really!
     
 

Anti-fouled and almost ready for the water.
     
 

But did it work?
     
    An Emphatic YES!

At full throttle, about 6 knots, instead of wet feet there is now a 2" drop down the drain to the W.L.  We therefore have raised the stern at speed by about 3". Just what I wanted to do.

There is a slight gurgle from the wedges when sailing, but no noticeable effect on either speed or weatherhelm, one of my worries. A speed buff would tell me the wedges must take 0.001 knot off my top speed,   Really?  As if I worry.  Having dry feet sounds better to me!

John Williams