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Mast Step Replacement 1:1 Dinghy by Ian_Grant

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About ten years ago I bought an old Bombardier Invitation 16 to sail at the cottage. This is a cat-rigged boat very much like a Laser 1 but slightly larger in all respects.  I had one in the 80's because I'm a tall guy and the Invitation is a much better fit than a Laser for my height and weight (which is at the top of the range for a Laser). It has 90 square feet of sail, a roomier cockpit, and more room to duck under the boom.  Unfortunately I sold it in the mid 80's because I spent so much time cycling that sailing just sort of fell off the map. And of course, when I met my now-wife shortly after, she mentioned she would love to learn to sail 😞


The lady had this one at her cottage, less trailer. When I went to view it, I checked the bottom (which was a bit beat up but hey, this boat went out of production in 1980), verified none of the screws holding fittings were stripped, poured water into the mast tube to verify it didn't leak into the hull, and looked over the rudder, tiller, daggerboard, mast, boom, and sail. The wood rudder and daggerboard needed fresh varnish, but everything looked good so I bought it. I did not think to sit the lower mast section into the hull tube and take a step back.


The very first time I rigged it I saw the mast was leaning forward and to starboard. AHA...that explained the circular access port someone had installed in the foredeck...they must have been fiddling with the mast step block inside. I sailed it for a few years like that, until I just reached the breaking point with its handling: forward leaning mast equals downward thrust on bow equals constant weather helm. In heavy gusts it would luff uncontrollably. Very annoying!  Plus it's embarrassing to have a boat whose mast leans to one side, when reaching across the lake towards someone's dock!


I decided to attempt to replace the mast step a couple of years ago, and if the result blew out in the wind and wrecked the boat then so be it. This old boat isn't worth much now anyway. Plus it would be an excuse to the admiral for me to buy a new RS Quest or even perhaps an Aero 9 since I usually go single-handed.


Step one: I cut a disc of wood the diameter of the mast tube in the hull, with a hole at its centre. I pushed it down to the bottom of the tube and used a cable installer long drill bit to drill through this hole and the hull bottom. Flipping the boat over I measured the hole as being 1-1/4" off centre to port (!!) which generated a huge offset at the masthead. Time to get to work.


Step two: From the hull bottom, I jigsawed a radius around the drilled hole. The radius was large enough that I was clear of the base of the mast tube. I then cut out a little more to starboard to allow the mast tube base to move over the requisite 1-1/4". Also cut out some more forward for similar reason. Here's a picture (when my brother saw this he asked, "What the HELL happened?!!"). You can see the base of the mast tube inside the hull. Note this is after I sawed/chiselled away the internal bracing of the tube to the hull bottom. This consisted of very heavy fiberglassing over a wood block formed from a few layers of plywood with a hole for the mast tube. I was able to cut through the fiberglass by slanting a sawz-all blade in through the big hole.  All the plywood was completely rotted and chiselled out in soft black lumps.




Step three: I sanded and cleaned the inside hull bottom around the hole to remove the remaining shards of fiberglass bracing, with one-arm access through the 5" port in the foredeck. Here is the port (wire for light bulb inside) and the prepped hull bottom. The large yellowish things are flotation/reinforcing/sound deadening foam.




Step four: I sat the hull on its storage chocks and braced it in place with stakes. A bolt was added through the hole I had drilled through the bottom of the mast tube, and a couple of tie-down straps were hooked around it and tightened to pull the bottom of the mast tube forward and to starboard. The bottom portion of the mast was inserted to decide on alignment by eye.



Here is a view with the mast tube pulled into proper alignment; compare it with the earlier internal shot.




Step five: I cut a three-layer square pyramid from baltic birch ply to fit around the mast tube. The rectangular recess in the hull bottom, from the previous step's block, was first filled in with two more pieces shaped to create a flat(tish) surface for the pyramid. The pyramid layers had to be cut in half to be placed around the mast, and in any case would not fit through the access port otherwise. I used my usual West System epoxy to glue everything in in one sitting,  one piece at a time, alternating the orientation of the cuts. Here is the result:




Step six:  Duct tape the hull bottom to seal the large hole and fiberglass the entire internal mess with cloth and resin. A very painful exercise using one arm through a single 5" hole! Here is a completion shot:




Step six (b):  Scrape the epoxy from one's right forearm! (Hand was ok due to latex glove).


Step seven: Demolish the bracing, flip the hull, remove duct tape, remove the bolt protruding from the mast tube, fill in the hole in the bottom and fair with resin. I don't actually have any pictures of the finished hull bottom. It's an ok job. I plan to refine it this spring.


RESULT:  She sails now with very little weather helm which feels much much better. I've been out in strong breezes with nary a creak from the step so that's a huge relief too.  All in all, a job I approached with a lot of trepidation but I'm glad I finally did it.  What took me so long?....I could have prevented so many dumps with the previous uncontrollable luffing...


Edited by Ian_Grant
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