I’m making steady progress on the build but keep discovering daft mistakes and trying my best to address so they aren’t terminal! Hoping to avoid any more so I have a couple of questions I’d appreciate any advice on:
1. Attaching mast step (forward one as I’m going for balanced lug rig)
2. Process for cutting mast partner hole and positioning mast step to get correct rake
1 - I’ve glued the cheeks to the stem and will screw from the outside of the hull when I flip over to provide extra strength.
How would you advised I attach the mast step itself to the stem+cheeks - should this just be 4? screws from inside through the step into the cheeks, to allow for adjustment later, or should I be gluing and screwing?
I’m a bit sensitive as my last build had a problem in a blow when the glued-but-not-screwed step sheered off. I’m hoping a screwed-but-not-glued step on this build won’t suffer the same problem!
- How do I establish the correct boat position fore-aft. I’m building on the floor as don’t have a cradle and clearly the boat can rock. Do I just move such that bulkhead 5 is plumb vertical and use that as primary reference? Or centreboard case being dead horizontal? Or...
- Once in place, should I cut the mast partner hole is the measured position but before I attach the mast step. Take her outside, pop the mast in, and eyeball the mast rake by moving the unsecured step until it looks right? Then secure?
- Did you have a more scientific way of working out the rake like a plumb line from the mast head or something?
For the benefit of other Forum members:-
Marc is "Building from plan. Not kit".
Please correct me if there are any boobs below.
Subject to verification, you could now be entitled to join us in the "I made a mistake building my Morbic Association".
Seriously, I'll consult Robin (tomorrow) for his recollections for Q1 & Q2, and get back to you. Meanwhile, Re Q2:-
Vivier's plans, MORBIC 12 - PLAN 12 - rev 3 Building frame Scale 1/157 November 2010, shows the waterline parallel to "The Girder". All frames are at 90deg to the "Girder".
The next sheet, MORBIC 12 Sloop version - Plan 21S rev 6 Longitudinal structure Scale 1/107 March 2019, and the equivalent Lug version, show the waterline, and the top of the CB case parallel to it (which is probably a good thing!). You could use a long stiff thing to project the top of the CB case forward, and establish 90deg from that.
IIRC we fixed the mast step flush up to the front bulkhead before using calculated measurements to establish the CL of the hole in the deck. I MIGHT still have the calcs. (Basic trigonometry?)
Irrespective of the above, it really might be worth investing a little time to make a cradle, if only for the benefit of your back!
See the Manual March 2017 Building Morbic 12 Page 15/21,
6.13.Mast partner and mast step (balanced lug version, or 6.14 for Sloop.
"The mast step is made of two layers of 10 mm plywood, laid over the stem extension. Glue and screw, on both sides of stem, wooden blocks allowing to screw down the mast step. Make a drain to avoid any water retention into the mast step mortice. The mast step is extended on port side in order to fasten an eye-bolt for the tack line purchase. Note that if you are not satisfied with the boat balance under sail, it is easy to replace the mast step with the mortice shifted forward or afterwards"
ie = Glue & Screw the blocks either side of the stem, then (glue?) and screw the step to the blocks. No need to go through the hull!
Haven't seen Robin yet (postponed till Monday) but he might reply on here anyway.