T&T: Paravane Rigging

Tue Sep 4 07:47:44 EDT 2007

Hello John,

My favorite subject, and one that can't be discussed  enough!

Seahorse came to us with a heavy, non-standard rig and  we spent a lot of 
time researching and modifying it so as to make it safer and  more user-friendly. 
A lot of info came from listees John Harris and John Boy and  others as well 
as look sees at various other installations. Credit also to  a Nordhavn 
engineer who revealed the answer to your question. The "fuse"  should be a 3/16" 
galvanized swivel in the tow wire between it and the 1/4"  HT chain. The SWL is 
850 lb and so the breaking strength is 5x that  should be sufficient if you 
snag something. I'm assuming you are using the 300  sq.in. fish.

I have not put a load cell on our rig, but I think  Beebe's figures of 10 psi 
are high - he may have seen that as a peak  (momentary) load but from an 
empirical standpoint but I can't see  it. On the other hand, boats such as Mona 
Mona, Chartwell and Tiki III have gear that is huge by comparison to ours  and 
that of the Nordhavns, even though they use the same size fish. Likely  Beebe's 
loads were higher because of roll period, etc. Our boat is quite  stiff 
without the fish, and so they help less than they would on a more tender  boat.

Our upper tow "wires" are 1/2" Samson XLS Extra which  has a breaking 
strength of 8700 lb and a stretch of 1% at  30%.

It would be interesting to know more about your boat. 

Let me know if I can supply more  info.

Regards,

John
"Seahorse"

>  I have finally started rigging my paravanes  and am having trouble 
deciding on what breaking strength to use for the line to  the fish. In the event 
that I snag a fish on a large object, I want it to break  away before damage 
occurs to the paravane boom, superstructure, etc. My problem  is that I have been 
unable to find information as too much force is generated by  the fish. Does 
anyone know of a strain gauge that I could insert in line with  the fish to 
measure the force being generated?

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