Bilge Pumps, employment, care and feeding.

[Fortis]

One more detail to add form personal experience. If the cause of the water's ingress is the stern gland packing letting go, then you are in for more trouble then large amounts of water gushing in form three inches behind the engine in a place that only an optimist would describe as merely innaccesible.

You see, the packing material is kind of fibrous...and the first thing that happens is that it utterly kills your electric bilge pump. The crud gets sucked in, clogs up the impeller and that is effectively that.
Having a clean and clear bilge is all well and good...but the stern gland letting go managed to pressuer wash the back of the engine (and the underside, and the little oil catcher pad that lived beneath it.)

All in all an educational experience.

I cannot tell you much about the manual bilge pump fitted in the cockpit. It was someone else's boat we were delivering and though we devotes a couple of very precious minutes to the search, we could not find the handle that made it work. My thought on that topic is that the emergency backup bilgepump should probably NOT require any kind of assembly at the point you need to use it!
A double action manual pump is also a good thing, not just because it moves twice the water for every stroke, but because it does it by having two seperate and discreet diaphrams...so if one fails you still have a "normal" pump.

In the end, a bucket and a small suckpump was what kept us afloat and going. A radio call to the coast guard asking them to ring the nearest boatyard with liftout facilities and get them standing by and ready for us was also good. We pretty much went straight up the hoistway and were out of the water and in a cradle with water pouring out. I still have no honest idea about what my solution to that particular problem would be if we were far from help. No way to draive a plug or patch into that form the inside, it would likely involve diving overboard with some sort of works-in-water duct tape or sealent and squirting it around the prop shaft so it gets sucked in  and then using more and more until it set. You do not get to fire up your engine again without a major haulout...but at least you don't sink. Could I do that with just a snorkel and offshore in semi-rough or rough weather? No idea, hoping never to have to find out.

As we stood watching the boat doing its colander act on the cradle (I had unhosed the through hulls so it could drain), just catching our breaths and not saying anything for a while, then Margaret said, "Okay, you've convinced me on spending the extra money for the dripless stern gland"



Alex.

[AdriftAtSea]

Yet, one more reason I'm glad my boat uses a small outboard for auxiliarry power.  The whole idea of trying to seal a rotating shaft that passes through the hull makes  me nervous. ;)

[s/v Faith]

whole idea of trying to seal a rotating shaft that passes through the hull makes  me nervous.

  Tough to avoid with an inboard......  ::)

Alex brings up a good point about issues with 'OPB' (other peoples boats).  You might address all of the issues discussed in this thread, but it does you no good when you step aboard some one else's boat.

  I usually bring my boat bag (1st mate calls it my 'Man purse') with emergency gear (handheld, gps, etc.) and I make a point of not making a point of it so on one is offended.  I am starting to wonder how I am going to fit a small gasoline trash pump into my 'little green bag'.....  ;D

[Auspicious]

If you have an inboard, you might look at using the cooling pump as an extra means of removing water.  Consider this carefully though, as running your motor dry, or sucking debris into the cooling system might complicate your situation.

The use of the engine's cooling system is another good alternative, but has some serious risks that must be considered.

I think this is an urban legend without any real basis. Take a look at the exhaust and think about how little water is really being moved. The flow rate on engine cooling water pumps are really pretty low.

This site cites a cooling water flow rate of about 15 gpm / 100 bhp for an indirectly (freshwater) cooled diesel (about 8 gpm or 480 gph for the 54 hp Yanmar 4JH4E in my boat). A Google search on shaft drive trash pump returned a bunch of options that include pumps with 2" to 3" inlets that will pass solids up to half the diameter of the inlet, run at 5(ish) hp from the main engine and push 200 to 400 gpm. They aren't terribly large or expensive ($150 to $400). With some creative valving such a pump would make one heck of a washdown pump as well. <grin>

[AdriftAtSea]

I'm not saying that it is an ideal solution, but a possible backup, if your main bilge pump fails.  An engine driven pump that has some serious capacity, like the ones you've described, are a great idea, but very few sailors will ever get around to buying and installing one.  The engine is already there....nothing to install. 

[CapnK]

One thing I've read about and haven't seen mentioned in this discussion - a 'sea locker', one place where all thru-hulls are located. This is basically a walled area that can flood up to (and above, in the case of heeling) the normal waterline, thereby containing any water which might come in through a broken or leaking thru-hull.

I guess it could be possible to build one in a manner where it also enclosed the engine area, for an inboard. Then if the packing gland gave way or even if the whole shaft fell out (!!! - but I have heard of that happening) the vessel would still only take on a limited amount of water.

Of course it won't help with a serious collision-induced holing unless the puncture fortuitously happens inside of the area it encloses ;), but it is another time-tested piece of strategery for dealing with hull-holes. :)

Good discussion.

Neal Petersen describes a holing in his book which happened while he was racing in the OSTAR. It was the result of a collision with a freighter. The leak was of a magnitude that he had to manually pump for something like 20 minutes of every hour, 24 hours a day, until he made it across the Atlantic (he was 1/3-1/2 way across when the collision happened). Obviously, he made it - and he claimed his upper body had never been as muscularly developed as when he came ashore :D, but ever after he has onboard a manual pump of huge capacity because he says he never wants to go through that again.

I don't blame him. :)

[Auspicious]

I think you are referring to a sea-chest as opposed to a "sea-locker." In commercial applications they are used to consolidate water intakes and reduce the drag associated with hull penetrations.

I have seen reference to them being used on small boats and extended above the waterline. Does the Amel Super Maramu do that? I'm not sure.

For bigger spaces you are essentially talking about watertight compartments. Ships are divided into a number of watertight compartments and then rated as 1, 2, or 3 compartment ships based on how many may be flooded while the ship still meets stability requirements.

If I recall correctly, the Titanic was the first 3-compartment ship and was declared unsinkable because no one conceived of a casualty that would open so much of the length of the ship to the sea. Oops.

[AdriftAtSea]

If you're going to go the sea locker route, make sure that the locker really is completely water-tight.  Also, might want to make two of them, one for the packing gland, and one for the other throughhulls.  The chance of losing the prop or the packing gland is very different from that of losing a regular throughhull, and you probably would want to be able to close off whatever seacocks you can—if they're all in one compartment, and the propshaft/packing gland goes, you might not be able to access any of them.

[oded kishony]

>The chance of losing the prop or the packing gland is very different from that of losing a regular throughhull, <

Which is more likely to happen?

~OK

[AdriftAtSea]

My guess would be the packing gland or prop shaft would be more at risk. 

If you properly maintain and inspect the through-hulls, prop shaft and packing gland, the through hulls are very unlikely to fail.  The hoses may fail, but if the seacocks are well maintained, that isn't all that much of an issue. 

However, if you wrap or snag something about the prop, there's a pretty good chance something will give...and if it moves or the packing gland is damaged, then water will come in via the prop shaft/packing gland. 

Also consider that the prop shaft and packing gland are not static fixed pieces, like a through hull is.  Movement leads to wear, and wear to leaks. 

[Captain Smollett]

Neal Petersen describes a holing in his book which happened while he was racing in the OSTAR. It was the result of a collision with a freighter. The leak was of a magnitude that he had to manually pump for something like 20 minutes of every hour, 24 hours a day, until he made it across the Atlantic (he was 1/3-1/2 way across when the collision happened).

I'd like to point out that as I mentioned in an earlier post, you REPAIR first.  IIRC, Neal did in this case, stuffing PFD's and whatnot into the hole to SLOW the rate of inflow.  Without doing that, he would not have stood a chance.  Even after stemming the flow of water, he STILL had to pump 20 minutes per hour.

Just Wow.

[oded kishony]

Care to say a few words about maintaining and adjusting the packing gland?

~OK

[s/v Faith]

Care to say a few words about maintaining and adjusting the packing gland?

~OK

Avoid them...   


Sorry.   ;D

 

FWIW, the cooling pump as a bilge pump issue.......

  ... There is a Hunter 30, that I will be  watching for a friend of mine.  He is just leaving, and his boat is set up with a y-valve on the raw water intake so I decided to try an experiment tonight. 

  I placed the pick up hose in a 1gallon jug with fresh water, while the motor was running and flipped the diverter valve.  It took approx 45 seconds for the Yanmar (20GM2...?) to suck the gallon dry (and of course flushed the motor with fresh water at the same time).  This was at a high idle, maybe 1100 - 1200 RPM's.

  That puts it at around 80 GPH, which is pretty low, unless you compare it to a manual pump, or a man with a bucket. 

  Actually, as I understand it the avg small (390-500) gph pump looses somewhere between 25% and 50% of it's capacity when actually installed due to restrictions in the hose, and pumping against a head. 

  80 honest GPH sounds pretty good to me if I needed it, if I had an inboard I think I would make the simple modification needed to take advantage of this additional de-watering capacity.

[s/v Faith]

Oh, and something I have seen that seemed like a great idea to me if you had an inboard.....

  THe coupler is often the only thing preventing the prop, and shaft from falling out of the boat and leaving a neat 1" or so hole.  TO safeguard against this, bolt a spare zinc onto the propshaft inside the boat, between the packing glad and the coupler.  THat way, worst case, if the coupler came loose the shaft would at least stay aboard.

[CapnK]

Ahh - 'sea chest' is what I should have written. I stand corrected! :) Thanks, Auspicious! (Grog fer ya, mate! ;D)

[Fortis]

The prgression of this thread escaped me, so I will try and cover a bit of ground here.

Firstly,  I am all about fitting a lovely pully driven high-flow pump onto the inboard (There is an outboard version of this as well...but only starts at 30hp and above in the Yamahas). Basically, when the poop hits the fan, turning on the motor gives you all sorts of benefits, you can run for help faster, use the combination of sails and motor to tilt the boat in such a way that you might lift the ingress point of the water above waterline long enough to plug it (thinking mainly of through hulls and waterline impact damage), and you even get to power your communication systems (while you can) without resorting to the housebank batteries so that you can call for help or advice.
Turning on the engine is a GOOD THING (tm).....Turning on the engine and using your raw water cooling pump as an auxilery bilge pump is a way of putting all of that at risk, for not very much return, and possibly creating a situation so that even if you get safely to port having fixed the rpoblem, you still need to spend $4-5K on an engine rebuild.

Thanks, but no thanks. I can move way more water with a bucket (and I say this with total certainty born of experience) without even breaking a sweat. Raw water cooling systems just do not move that much water volume and they are fragile and finicky.

However clean you kkep your bilges, however pristine the boat interior...I promise you that on that faitfull day, there will be nine kinds of poop floating around your ankles. Just take it as a given.

I like the dual action manual diaphram pumps as a back up. They move an amazing amount of water with not much effort.


Maintenance on stern glands is a tricky, you sort of have to live with the boat long enough to know it and hear what it wants. I know lots about how to replace packing, what kind to use, how to tighten down and monitor and what rate of drip is considered optimal to show that the internals are being lubricated and the shaft is not being over-gripped.... And yet I got caught out because I did not have a history with the boat and it just happened to choose me to go "pop" under. When I spoke to the owner later he told me three or four things that would have had me never taking the boat out without having replaced the packing (probably three months earlier)...but he had just kept tightening down the nut....which should not be something that neds to happen after  the first couple of weeks at most. If you need to tighten the nut to slow dripping and the packing has been in there for five years or more...it means you need to repack, not adjust). But the owner did not know that, had "fixed" the problem and handed me the boat. I checked the engine and shaft before we loaded everything aboard (thereby blocking most access to the area). It was behaving perfectly so I had no cause for concern....

On many design the coupler is indeed the only thing stopping the shaft form sliding back...but what usually happens before the shaft exits all the way is that the prop runs into and jams the rudder. Does't that just make you happier?
We were on board a H28 with an offset prop that had the coupler throw its bolts just after a full engine service (that is the time it is going to happen.) and the shaft pulled all the way back to the rubber coupler....fortunately the bolts that got thrown were the ones at the gearbox end and not the shaft-clamp.

Attaching a zinc along the shaft may be a good solution, but many boats in our size range have the shaft sitting so close to the floor and in such a narrow space (usually with such a short shaft length bwteeen gearbox and sterngland) that this is not practical) At this point, positioning a zinc where it actually does the most good just in fornt of your cutless bearing (and making sure the cutless strut is strong and good) will achieve the same result of stopping the shaft from exiting all the way while putting the zinc to the use it was intended.

As a method of caring for and watching out for stern glands....I would nowadays describe them as very old tech and a generally bad idea and replace them with the now very reasonably proced dripless stern glands.
these are a very nifty thing and last for many decades without need of replacement or adjustment anything (In boats with our range of horse power. At 60 hp and up, there start being cooling issues to watch out for). Dripless systems work by having two specially made ceramic surfaces acting as bearings and water excluders, rather then pressuring kevlar, teflon or tarry rope against the spinning stainless shaft (which also acts like a brake). The ceramic dripless system has far less friction, thus upping your engine's output, and it does not wear grooves into the prop shaft (like kevlar packing, and to a lesser extent teflon) will over time do.

Finally, on the topic of sea chests as a way of preventing sinking....On boats our size it seems a great way of losing a lot of space quickly and it makes all of the pumps work harder as they now have to lift the head of water higher to get in over the top of the seachest. I am not fond of the idea of encasing the engine as service for an inboard in a 26foot boat is already akin to nuerosurgery on a gerbil....Conducting neurosurgery on a gerbil that happens to be lying at the bottom of a bucket (with tubes, wires and hoses running in over the lip) would be more then impractical.

One system that I have seen on an ocean racing boat that had preciously had the poop beaten out of it in Bass Straight and had its propshaft take out its rudder post (tearing the rudder post sleave to shreds in the process) and thus letting in two huge streams of water (the solution for the rudder post going was ingenious, by the way). What they ended up with by the time I crewed was effectively a clip on watertight box around the stern gland and a second sterngland through the bottom lip of that clip on box (the bit that was glassed down to the hull). This worked on the premis that both were unlikely to fail at once and they had the engine well forwards for racing advanatge and so had a long span of prop shaft inside the boat. Apparently the box, when allowed to fill with water under some pressure would still only leak a very little bit and the skipper took comfort in that. He also had a 14ga stainless tub replacing the thin copper sheath with fibreglass wrapping that used to be the old rudder post shaft.

"Lose the boat again, or put an extra 9kg of "stuff" on board to keep it safe and strong? Easy choice for the man with the checkbook!"



Alex.

[oded kishony]

Thanks Alex!

Would you list some symptoms of a failing stern gland? I'm suspicious of mine and would like to know if I ned to replace it. Suggestions (brand names etc) for replacements would be welcomed too. How difficult is it to replace with a ceramic stern gland? Is it something an amateru can do or is it best left to a pro? Price range?

Thanks,
Oded Kishony

[Fortis]

I'm just heading for bed, so I will get back to this one later. A stern gland in good condition shoudl ddrip one drop every 15-20 seconds when the motor is running (shaft turning) and effectively not at all when the shaft is still.

Repacking a stern gland is a joy on some boats and a fraught experience in human origami in others. Maintenance of that area was almost never on the designer's or builder's minds in the case of most small boats (and not a few large ones). Replacing the packing is done with a large spanner and a small hook. Rather then buying an $8 bit of twisted spring steel wire to extract the old packing material, I like to use a long shanked fishing hook (small size, but with a long shank) and to straighten out the hook bit somewhat, so that the barb does all the work of hooking out old dead packing rings.

Basically, the game is that you unscrew the big tension nut at the front of the stern gland, pull it as far forwards along the shaft as the situation allows and start fishing out the old packing material. This is also a good time to see if the shaft is at all worn or grooved in the area that undoing the nut has oncovered. Oh, by the way, in some models of stern gland, the packing lives inside the sleeve of the nut, and in others it lives in the gland itself, not sure what type you have, they are equal in terms of quality, just different.

Next, cut the lenght of packing material you have bought fomr your chadlery (and which is the right size and type) into three or four rings that just form washers around your prop shaft. Nice clean cuts are important. (some stern glands only have room for two rings of packing, not a huge fan of those). Insert the rings into the place theold ones got hooked out of in a way so that the cut ends do not overlap. So if the first ring you put in has the cut ends at the top, the second should have the cut ends on the bottom, and so on. Put a little white winch grease on the threads of the nut and tighten down. Do not over do it, as the boat will need to go back in the water in order to fine tune the nut's tightness so as to get the correct amount of drip (which shows that the innards are getting cooled and lubricated with water and that the shaft is not being bound too tight).

Dripless ceramic systems are around $350-500 australian...so figure half to two thirds that in the US. They can be fitted by an amatuer in most cases, but it depends on the boat. Some prop shafts need the rudder removed and seemingly half the back end of the boat disassembled, some just need two or three friends, some not-overly alcaholic libations and a full day.

A good way to save money if you lack full confidence to take the job on yourself is to take off the old stuff (disconnect and remove shaft, remove stern gland etc) and then call in the boat yard to come install the dripless system and reinstall the shaft (they can do the balance on it while they are at it). Cuts a little over half the cost off and leaves you with "professional" results (of course sometimes that means a proffessional orangutan weilding a pickaxe...but I presume you know the qaulity of your local boatyard).

Anyway, that's about it for the evening. Good night.


Alex.

[oded kishony]

> Repacking a stern gland is a joy<

Thanks Alex

:)

[prairie_sailing]

Okay, so I read about other people's bilge pump issues...decided to check mine out today.  To my shock and amazement I had about 12 inches of standing water in there (the boats out of the water).  Upon looking into the water issue I found that one of the drains from the cockpit came loose.  Seems I've been getting some rainwater in for awhile.  I've got to add this to a list to check on a more regular basis.  Also, I don't have a bilge alarm...might have to look into this.