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Marieholm 261 rigging settings

Postat: tor 21 jun 2018 15:14
av mward
Hello, I have a Marieholm 261, I think the only one in the US. I am getting new rigging made and need to know some settings. The rig on the 261 should be pretty close to a 26, so numbers for that boat will probably work.

How much rake on the mast?

How much tension on the cap shrouds?

How much pre-bend in the mast?

Thank you in advance.

Here is my blog where I am documenting the rebuilding of this boat. When I got it it was in terrible shape.

http://www.marieholm261.us/

Re: Marieholm 261 rigging settings

Postat: tor 21 jun 2018 16:25
av maja
Try North Sails Tuning guide >> http://ifboat.se/trimguider-pdf?view=si ... ager&id=49 or http://ifboat.se/trimguider-pdf?view=si ... ager&id=48

But in my opinion the tention reading 37 on the upper shrouds with the Loos B meter is too much and may perhaps damage the boat. Not more than about 32-33 is recommended.

Re: Marieholm 261 rigging settings

Postat: tor 21 jun 2018 18:58
av mward
I wrote to Göran Helmer about this, and this is what he had to say:

The way I put up the mast and rig is as follows. First I set the
forestay so the mast is standing straight up and I tighten the forestay
turnbuckle accordingly. The I take the upper shrouds. Measure them so
they have the same lengt on each side. You can trust the the
shrouds/stays are exacly the same lengt. I the tighten the upper shrouds
the same number of turns on each side. I use a small pair of tongs for
this. I tighten the tong by hand rather firm. Until the mast makes a
slight bend to the aft of the boat. Then you do exacly the same with the
lower shouds. You tighten less hard than the upper shrouds until the
light bend of the mast is straigtened out. Thus the mast is straight
again with no bend.

No firm numbers but a good starting point. Sounds like no rake and no prebend. Kind of odd for a swept-spreader fractional rig to be set up this way but he would know more than anyone.

Re: Marieholm 261 rigging settings

Postat: tor 21 jun 2018 19:03
av mward
Maja, you think 380kg is about the right amount? 38 would be 780kg, that does seem very excessive.

Re: Marieholm 261 rigging settings

Postat: tor 21 jun 2018 20:49
av maja
Sorry, the readings I suggested should refer to Loos Model PT-2.

The reading 32 corresponds to 380 kg and 12 % of breaking load of a 6 mm diameter wire.
The reading 33 corresponds to 420 kg and 13 % of breaking load of a 6 mm diameter wire

In my opinion, this is suitable. I use those values for my own IF. With an almost straight mast (1 inch or less of prebend) , it results in a reading of about 20 on a 5 mm diameter forestay.

Re: Marieholm 261 rigging settings

Postat: fre 22 jun 2018 20:06
av Nils D
maja skrev:
tor 21 jun 2018 16:25
But in my opinion the tention reading 37 on the upper shrouds with the Loos B meter is too much and may perhaps damage the boat. Not more than about 32-33 is recommended.
Do you still use 20 for the lower shrouds, as the North Sail guide suggests, or do you use some lower settings on these too?

Re: Marieholm 261 rigging settings

Postat: lör 23 jun 2018 07:42
av maja
My lower shrouds are made from 5 mm diameter wire. I use to adjust the lower shrouds so that the prebend will be not more than about an inch. As I remember, my Loos PT-2 reading will then be about 18-20.