Do you have thru-hulls above water line?

[Exile]

Originally Posted by GordMay

Remember: At sea, a boat is [almost ] always manned, whereas dockside it's mostly unattended.

More than two-thirds of the reasons why boats sank could be considered preventable. Half of those preventable claims, or one-third of the total, involved boats that sank due to the gradual failure of a part below the waterline.
And, according to BoatUS records, for every boat that sinks underway, four boats sink in their slips.
In 50% of dockside sinkings, water found its way into the bilge through leaks at underwater fittings. The majority of the leaks are at stuffing boxes, followed by outdrive or shift bellows, failed hoses or hose clamps, sea strainers, and drain plugs.
It is also interesting to note that the finger was pointed at fittings above the waterline in 9% of the sinking claims.
Water falling from the sky, either rain, snow, or sleet, accounts for 32% of sinking claims.

Very informative and most useful for chasing down essential preventative maintenance. The 4 out of 5 sinkings at the slip stat is consistent with what an experienced surveyor friend has always told me. The other comment he mentioned I always found shocking, namely the large number directly attributable to cheap hose clamps, often installed at the factory on newer boats. Even ones marked 316 SS lack SS pins which can & will corrode causing failures.

Fwiw, and last time I checked, ABYC did not specify seacocks for above waterline thru-hulls. It would certainly be the better practice, however.

[psaltydogs]

Here is a problem I currently have. Maybe a good through-hullologist can answer this:
My cockpit drains need to be re-located to the aft end of the cockpit. If the same set-up is done, using two-inch hoses and valves, the tops of the valves will be at the water line and routing the hoses across to opposite floor drains will be impossible without creative work using stainless tubing.

I propose to have no valves, but just to use through-hulls with hose barbs on them. This means the hose connections at the low ends will be below the water line.
This might seem to be heresy but it looks like I have to do it.

[SuW]

On an hour-long starboard tack on our previous boat (just purchased, with the old owner aboard) someone went below and found that water was flowing in from the head sink to the saloon floor. The thru-hull was about 18 inches above the waterline but siphoned in with the force of the wake flowing past.

"Oh," said the PO, "Yes, you have to close the head sink seacock when underway."

This from the man who had built the boat with no seacock at all on the galley sink drain...
"It wouldn't fit. No room for the handle."

We loved the boat by then, nothing that money couldn't fix, right?

[Mark Johnson]

Originally Posted by djblizzard

For those of you who have thru-hulls located above the water line and think they do not pose a sinking risk, let me tell you a story.
Last night I got a report of a sinking boat at my local club. The boat in question is a 30 foot cruiser used as a live-aboard here on Lake Ontario. It's been lived on over the last few years by a friend of mine. The water was well above the floorboards and actually above the cockpit deck floor by the time we had rounded up all the pumps we could find. With 5 pumps running full blast, we could just get ahead of the rising water. It took 4 hours of pumping to slowly lower the water level to a point where the problem could be found. With the water hovering at 1 degree Celcius, it was not fun groping around the bilge to find a dislocated exhaust hose and its clamp.
It was also discovered that, what previously was a small leak, led to bilge water and waterline rising until the previously "above the waterline" thru-hulls for the shower and sinks, weren't, and water was gushing into the hull from them as well. The problem was cascading to a really serious issue. A few more minutes and the boat would have been on the bottom.
IMHO all thru-hulls need to have a shut-off valve.

Our self built trimaran, just like the two before it, had all Marelon plastic through hulls. I have a great deal of confidence in them.


Below the waterline, flush heads work best, and starting out below flush by 1/16" is best, as they swell a bit over years.


Above the WL, be sure to paint them for UV protection. Two part LPs are best, and WILL stick to a well sanded Marelon mushroom head just fine.


Like always, use GRAY two part primer under the white LPs which can not block UV rays otherwise. Gray primer is opaque, but white top coat is translucent.


Seacocks are required everywhere on monohulls, but on multihulls, above the WL, going without on sink or cockpit drains is OK, if you keep wooden plugs near by.

[GordMay]

Originally Posted by argonauta1

In most boats, should the exhaust hose disconnect within the engine area, the siphon loop should prevent flooding ...

FWIW: A leak (or disconnect) in the exhaust (between the heat exchanger or engine block & exh’ outlet thru-hull) will allow cooling water to flood the boat.

[Aquasition]

I had something like this happen to me as well, twice, due to two different underlying reasons, both that started with different failures of the aft bilge pump system in my 1988 32' Wellcraft St. Tropez. Note that I have since put in place the Siren Marine's MTC system to alert me of many of the warning signs that lead to it, and so much more, and I can sleep much better at night knowing this. (Well worth the money!) I highly recommend others look into it as well. Feel free to PM me if you want more info -- I don't want this to sound like an advert for their system and hope this doesn't violate any forum rules.

Here's what I think happened the first time:

• Bilge pump thru-hull exterior fitting had sheared off unbeknownst to me. (Not sure how or why, as I always use fenders when docking/rafting up, etc. Could have happened during commissioning and was on the water side, not my dock side, so I never saw it.)
• Bilge pump hose eventually fell below the thru-hull since the fitting holding it together had sheared off.
• Bilge pump was merely circulating water in the bilge.
• Batteries ran down to dead (I don't leave my converter in the on-position.)
• Bilge pump stopped operating.
• Normal water intake from shaft and rudder seals added up until there was enough water to go below a thru-hull leading to water coming in at a much faster rate.

The second time was similar, except the underlying reason was:

• Even after cleaning it, I had some oil remaining in the bilge due to an engine problem I had previously fixed.
• Automatic bilge pump float switch got stuck in the up position, possibly due to added buoyancy from the oil. (nothing was obstructing.)
• Batteries died.

Fortunately both situations happened on days before I was going to take friends out on the boat and after not having been to the boat in a while I stopped by very late the night before to drop off some stuff and make sure she was ready to go. Both times I immediately noticed no DC lights worked. Checked AC connection, was fine. Checked battery meters on the panel, dead. Immediately turned on charger. Noticed bilge pump indicator at the helm turned on. Opened center engine compartment cover, saw water was very high (but not yet touching engines).

In both cases I dropped in a second 12v emergency bilge pump with hose going overboard. and had the water level down significantly rather soon. (I should probably also keep an emergency AC-powered pump nearby, but I know others at my club have them, too.)

In the first case (sheared thru-hull fitting) I did some engine compartment contortionist routines and reconnected and secured the aft bilge pump to the external fitting which I properly fixed early the next morning.

In the second case (oily bilge) I cleaned the bilge as much as possible, raised the float switch a bit, and even added a weight (53 cents, two quarters and 3 pennies to be exact -- is this where the term pennyweight came from?) to the float and tested it many times to ensure the added buoyancy if it happened again would not be a problem.

Fortunately in both cases she wouldn't have sunken too far because at my home club on the Charles River in Watertown (near Boston) the depth at my slip is only ~3 feet (plus a couple feet of soft silt)... but had I been docked out in the harbor or beyond it could have been a much different story.

I now have complete monitoring and alerting due to the Siren Marine MTC and various sensors and alarms covering bilge pump activity, battery voltages, high water alarms, temperature, motion, etc. that send alerts right to my phone (text and app alerts) and email. Fortunately I have not had any further issues but when something fails I'll be in front of it!

[Aquasition]

As an aside -- all of this is making me consider also putting in an AC-powered bilge pump since I usually have shore power and don't leave my battery charger/converter on to avoid cooking the batteries... What do others think?

[stormalong]

Originally Posted by Aquasition

As an aside -- all of this is making me consider also putting in an AC-powered bilge pump since I usually have shore power and don't leave my battery charger/converter on to avoid cooking the batteries... What do others think?

A modern smart charger would keep your batteries up without cooking them.

[Aquasition]

Originally Posted by stormalong

A modern smart charger would keep your batteries up without cooking them.

Thanks and great point! Unfortunately in order to remove the thru-bolts to remove my original 1988 charger/converter, I'd have to disassemble the galley and remove the fridge that blocks access... not something I want to undertake right now. But, useful info for others and for me in case the issue is forced one way or another...

[stormalong]

Originally Posted by Aquasition

Thanks and great point! Unfortunately in order to remove the thru-bolts to remove my original 1988 charger/converter, I'd have to disassemble the galley and remove the fridge that blocks access... not something I want to undertake right now. But, useful info for others and for me in case the issue is forced one way or another...

As an alternative you could mount the new charger elsewhere. Just disconnect the old one. The newer generation of chargers are quite small.

Put the removal of the old beast on your future plans list when some other project forces you to get into that space anyway.

[Aquasition]

Originally Posted by stormalong

As an alternative you could mount the new charger elsewhere. Just disconnect the old one. The newer generation of chargers are quite small.

Put the removal of the old beast on your future plans list when some other project forces you to get into that space anyway.

Valid points again -- thank you; The main reason I want to remove the old one during replacement is because it apparently weighs quite a lot (I was told "hundreds of pounds" by someone with the same boat who had to remove his when it failed), and I don't want to carry around the weight of a new one plus the old one given that the boat is already quite heavy already...

Maybe I'll attempt removing the fridge to see how easily I can('t) get to it...

[stormalong]

If you know the make and model of the old charger you should be able to find it's weight. As a rule of thumb, a 40 amp transformer type (ferro-resonant) charger should not be over 40 lbs (20 kg). People tend to exaggerate weight when they are on their back holding it up over their head in a tight place.

For the sake of extending the life of your batteries and piece of mind just do it. Easier than fitting a second, shore power bilge pump and and wiring and fittings.

[tazziboy7]

Maintenance.
If you need more then why not add a check valve like in a wetvac?