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Sailor Thom Davis shares how he solved a problem often associated with folding trimarans. Namely, the lack of an easy method to tension and de-tension mast shrouds in between the folding and unfolding of the boats.

He explains what he is now doing for his boat below. A great write up and video here … and many thanks for sharing it with us!

Thom writes:

Hi Joe.
One common issue with folding trimarans is the likelihood that the shrouds must be tensioned and detensioned each time you fold and unfold. Furthermore, there is a similar likelihood that you want to have the mast centered and you want the shroud somewhat tight to help keep the boat stiff so you can point. Most modern small trimarans use dyneema shrouds with an adjustable lashing to achieve this but that entails a lot of tangles and knots and once you need to untension, the knots are difficult to undo without a marlin spike–and basically it takes a lot of time and bother-each time.

My boat, SriRacha (SeaRail 19) came with the basic system…shrouds short and lashings to the chainplate. Truly a bother. Difficult to get the mast centered and difficult to tension/detension.

After a couple years of dealing with this, I finally created a “no knot” system with variable lashings. It uses Ronstan Shocks to create a cascade. Mine is 8:1 to give a good tension. When you make the shroud, instead of a sailmaker’s thimble, you thread half the Ronstan Shocks onto the end for the chainplate. For my boat, since the chainplate is not accessible under the tramp, I made a continuous loop of dyneema with the other half of the shocks onto that loop. Get the mast centered and mark where the lashing line comes through the final shock. You will create an eye splice there. Then you luggage tag (with an eye splice) the remainder of the lashing line there. To tension the mast after unfolding, simply pull the lashing through to the eye splice and insert a soft shackle luggage tagged to the eye. Now the shroud is tight, the mast is centered and you have a handle to pull when you are ready to detention.

The first minute of this video shows the system.