[C320-list] Leak in bilge

[Dennis Harris]

Kurt,

Just a thought.  On my boat, the hatch directly over the table has a small 
leak.  It does not leak in a normal rain, only if there is considerable wind 
with the rain from a certain direction.  Afterwards, with windy rains, there 
will be a few drops on the table or on the cabin sole. It doesn't stay long, 
so unless you check it then, you will not see it.  But the water from a big 
windy rain will collect in the bilge section where the bilge pump is. Of 
course, if you have dried the bilge and the water reappears when there has 
been no rain (and it's not coming from the shaft packing), then you would 
suspect a leak at the keel bolts.

Dennis Harris
C320 # 694

-----Original Message----- 
From: Bruce Heyman
Sent: Thursday, January 20, 2011 1:28 AM
To: C320-List at Catalina320.com
Subject: Re: [C320-list] Leak in bilge

I'm not a mechanical engineer but this problem intrigues me.  I believe it
does not really matter if you tighten the keel boats in the water or on the
hard. As my brain at this point can only remember that in some point in the
distant past I took physics I hope I'm not totally botching the concepts.
In no particular order:

1) The keel bolts do hold the weight of the keel, but more importantly they
compress the area between the keel and the bilge putting the keel trunk in
compression.
2) The high torque requirement, 235 foot pounds, is to perform item one
above and does so by stretching the stainless steel bolt.  Hard to believe
that a 1" SS bolt stretches but it does and I believe this would be called
preload.
3) The bolt and nut is a machine that provides significant mechanical
advantage.  Basically the threads form an incline plane making it much
easier to turn the nut compared to the lateral forces generated along the
axis of the bolt.  Thank you Archimedes (wonder if he was a boater?).
4) The torque measurement is not only a measure of the work done in the
machine (threads) but also the friction on the nut face and the surface of
the threads.  That is why it is important to take the nut off, clean both
surfaces and make sure they are dry and free of contaminants.
5) If the breaking strength of a 1" - 8 threads per inch bolt is 60,000 lbs
the clamping or preload would be 14,992 lbs when torqued to 249 ft LBs.
6) As our keels only weigh 4400 lb's this means that one bolt when properly
adjusted would be able to hold the weight of more than three keels.
7) As we have multiple keel bolts, all torqued to 235# the preload more than
swamps out the relatively trivial weight of a single keel.  I don't remember
how many keel bolts we have but if we have 6 then the total preload is a
staggering 90,000 lbs.  This is 20 times the weight of our keels.

Maybe I'm all wet (pun intended) but I believe you are free to torque your
keels in the water.  Furthermore it is safe to remove one nut at a time and
clean it up before you reinstall it and torque it to 235 ft lbs.

Bruce
Somerset #671 SoCal

-----Original Message-----
From: c320-list-bounces at lists.catalina320.com
[mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Allan S Field
Sent: Sunday, January 16, 2011 11:04 AM
To: C320-List at Catalina320.com
Subject: Re: [C320-list] Leak in bilge

Bruce - you are correct in that the Association has the torque wrench and
sockets to tighten the keel bolts. However, the boat must be out of the
water with at least 70% of it's weight supported by the keel. Think about it
- if the boat is in the water and the weight of the keel with a gravity
assist is pulling the keel down, what torque wrench and what sailor have the
strength to pull that puppy up?! In fact, the bolts first get loosened
before torquing. And yes, loose bolts do weep and need to be torqued after
the first year then never again, at least according to Gerry Douglas. -
Allan

Allan S. Field
Sent from my iPad

On Jan 16, 2011, at 1:27 PM, "Bruce Heyman"<bruceheyman at cox.net> wrote:

> Can be tightened in the water.  The Association has the equipment you need
to do this job.  I thought the manual said to tighten them after the first
year and then you were done forever.
> Bruce
> Somerset 671 SoCal
>
> Bruce Heyman
> (949) 289-8400
> BruceHeyman at cox.net
>
> -----Original message-----
> From: Kurt Budelmann <krbmd77 at charter.net>
> To: "Catalina320.org" <C320-List at Catalina320.com>
> Sent: Sun, Jan 16, 2011 18:02:06 GMT+00:00
> Subject: [C320-list] Leak in bilge
>
> Hey, I am having a slow leak in the bilge right by the bilge pump.  No
collections of water fore or aft of this location.  Can water leak down from
top of mast?  Can water leak from the keel bolts?  Also there is a floor
joist crossing at that location but I can find no evidence of leaks from
ports.  I don't think keel bolts were ever re- tightened and the boat has
never been out of the water since original launch.  Can the bolts be
tightened in the water or does the boat have to be on the hard?
>
> Kurt R Budelmann
>