Saturday, December 6, 2014

Stern arch and dinghy lift

Well this turned out to be a pretty major project, but one which wound up giving us a great deal of confidence in the outcome.

Initially what we wanted to do was:

- strengthen the dinghy davits.  We never did hoist a dinghy on the original arch but one day I did put a hammock chair on the davits and they were flexing inward about half a foot when I sat in the chair.  Now, I've put on some weight through the years, but this didn't seem right.

- we wanted princess seats in both corners.  We hadn't yet decided how we would do this because we have matching lazarettes in each corner which wouldn't be able to open if we had put permanent seats over the top of them.

- increase area for solar, wind generator, toys

The original arch.  You can see the arch connection points to the former stand-alone stern pulpit.  This swung wildly side to side when agitated.

We worked with Chris over at Svendsens to design what we were looking for and, of course, what we needed was a full rebuild, not a retrofit.  There was a very good reason for this though.  Turns out the original arch was simply built on top of the stern pulpit.  Well, you see....., stern pulpits support lifelines and are not built to support up to 1,000 pounds (think arch steel, solar panels, outboard, and dinghy - possibly filling the dinghy with water).  So our rebuild design started.

Starting to line everything up, shape, height, etc.

 The big change we made was using the recessed stern to counter balance weight and motion and spread the contact area over a wider region, including backing plates to spread the weight.  We also used single rods of steel to wrap from one side to the other, again creating significantly more strength, 3 of them in fact.

By using the recessed stern we also gained acreage, we had more square footage created by bringing the arch abaft and this area became our princess seats.  This allows us to virtually sit over the water and still open the aft lazarettes.  AWESOME!

Designing the princess seats.  Note how the seat adds to the available space by floating over the stern.

The princess is happy!

Next was designing the dinghy lift.  What we wanted here was something we would be inclined to use regularly (read: come home buzzed and not be so lazy or drunk to leave the dinghy tied up but floating and ready for someone to steal).  What we wound up with was a pulley system which lowers a lift bar all the way down to the dinghy, then simply clip on the connecting lines and run the lift line through the pulleys, a clutch back to the cockpit and a winch.  Up she goes, takes 90 seconds.

The pulleys run under the solar panels with the line eventually running down the arch through a clutch and block back to the cockpit and a winch.

Solar panels and wind generator were added to finish things off.  See separate blog entries for info on those. 

Our cardboard wind generator  (just kidding!)

At the end of the day we had what we hoped was a 'beefing up' project actually turned into a major boat budget item.  But we couldn't be happier and now feel confident about the structure and support it offers.