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dfarrell@ridgecrest.ca.us
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Some warnings for nylon bolts to hold down the keel on the P-19.
Nylon has a wide variance in yield strength. For cheap nylon I've seen 9,000
to 12,000 psi yield.
The nylon bolt should hold the keel weight, 400 lbs and break at about the
weight of the boat, 1200 lbs. This is just rule of thumb.
The breaking force (lbs)of the nylon bolt is its yield strength (psi) times
its minor cross sectional area. From the cross sectional area you can
calculate the diameter of the bolt.
The minimum diameter nylon bolt (9000 psi)to hold just the keel weight is
.240 inches (this is diameter on inside, not outside of the thread).
The minimum diameter nylon bolt (9000 psi) to break at the boat weight(1200
lb) is .41 inches.
So if you want a bolt (9000 psi)that will hold your keel in the event of an
overturn, but yet yield when you crash into a sandbar/ submerged SUV you'll
need at least a 3/8 or 1/2 inch nylon bolt.
Please note that nylon varies considerably in its yield strength, so this is
just a nominal calculation. Also I hope someone checks my calculations for
possible errors.
Bungee consideration - how far does a bungee have to stretch to hold 400
lbs? May want to consider multiple bungees under alot of tension to hold
keel.
Jim Nolan P-19 #426 Panache
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