Here's another sketch from Chris Morejohn of a 34ft boat with a junk schooner rig. 

This puts the foremast into the space ahead of the double berth, rather than through it. With a schooner rig, similar to the 34ft Benford dories, it gets much easier to find or make masts. What's the thinking behind putting most of the sail area into one large sail, Frederik? I found 54sq m a bit much to handle, which is why I went back to a ketch rig.

Thanks for the replies.

Arne. 

Are you using modulus of rupture in your calculations? For a 310/62 mm hollow spruce that would be 72 Mpa with a breaking strength of approx. 16300 kpm...

If I was aiming for a minimum of 10000 kpm, then a hollow Spruce pole 260/120 mm diameter with 60 mm thickness would be enough..?  Weighing in at ca 140 kg.  Theoretically...

Another possibility might be making a hybrid mast consisting of a 8 meter  alu 6082t6 pole, 240/10 mm with a wooden 6 meter topmast (1m bury). Appr. 200 kg.. 

Scott.

Yeps I am happy with the design. Going back and forth the last couple of months has been very interesting. The brief was; ocean going, shallow draft, junk rig, outboard engine, two persons. Now I'm doing the rounds and finding out about materials, prices etc... we'll see..

Frederrik,

I am excited to see you are considering building a Chris Morejohn HF design with a junk rig. I absolutely love the lines on all his drawings. I had a few email exchanges with Chris but eventually it became clear that boat building was not the way for me to go right now. I share your opinion. If I ever build a boat the HF designs will be right at the top of the list.

I would very much like to see the HFJY34 drawings from your post brought to life and sailing.

If I am going to build a boat, it will be this one.

 I asked Chris Morejohn to design this boat for me and with the help of Arne we got the rig looking good.  imo...

some numbers  

LOA 34 ft

Beam 10 ft

Lwl ca 34 ft

Draft 20 “ board up  6 ft  board down  

Displ 6-8 tons

Main 56 kvm  

Mizzen 9 kvm

CE calculated without mizzen

CLR with rudder and  daggerboard down (small daggerboards aft not included)

lead ca  15 %

chord/wl ca  55%

mast height ca  13 m, ca  11,5 m above partners

max rightning moment  ca 3400 kpm

FoS 3... preferred mast break/bend strength ca  10000kpm

Now.. the mast..... 

When I use the tables in “practical junk rig”, we’re looking at a mast with a breaking strength of 19000 kpm hollow Douglas mast. Diameter 31 cm at partners. Hard and probably very expensive to make..

I would prefer a aluminium mast and have been looking long and hard at the Nedal pole as used on various other vessels

When calculating the strength of this alu mast (220 mm/5 mm Nedal) on a vessel like Tystie I find the bending strength to be quite low. Approx 3100 kpm.... barely the same as the max rm for a boat like Tystie.. or for the HFJY34 for that matter

Are my calculations way off?