Inside my E36C there is a turnbuckle from the deck to the mast. What is the purpose of this and what is the proper tension? see photo
I remember when Bob Perry called this a "tie rod" when he had it go from cabin top to base of mast step on his V-40. Other boats have the collar that the turning blocks shackled to pinned right thru the spar.
Same purpose for all -- keeping the cabin top from being hauled upwards by the loads on halyards. (Main halyard load is not too bad, but you can get some major force on a spinnaker or jib halyard -- and on a heavy air reach all three are loaded.)
Keeping the boat sides apart is not really why it's there, even tho it would lend some strength to that idea.
Loren
Loren. In this case you are wrong. It had to happen sooner or later
The turnbuckle is there even if there is no connection between the cabin top/deck and the halyards. If you draw a vector diagram of the forces you will see that as the shrouds pull up and in they will compress the deck between the shroud under tension and the mast, pushing the deck upwards. So by keeping the deck from flexing upward too much the deck also helps keep the hull from pulling too far inwards towards the mast, and is thereby stiffened.
-Sven
I'm siding with Bob on this one.