[Yachtjocky]

As already mentioned, Tuna Tubes are for keeping bait alive, usually small tuna but they need to be face down in a tube with a good water flow coming in at the bottom. This is probably why a 2" thru' hull fitting was reportedly installed.

As for bilge pumps, I would have to ask how many 12 or 24 volt DC submersible bilge pumps are installed in say a Feadship. Mostly there is a 120 or even 220 volt bilge pump with a manifold with a fire/bilge pump as a back up. Then there is a diesel powered back up pump that is sometimes portable or plumbed into hard pipes.

Having worked on quite a number of Nordhavn's I would have to suggest that the cause of this sinking was due to human error, poor workmanship by the installer if that was the source of the water ingress, poor follow up checking by a captain or owner and poor operation of the vessel by leaving water tight doors open.

Did the Captain or owner carry out regular checks of the bilge system, did they check bilge alarms before a trip, did any body ever put water in the bilge areas and use the hydraulic pump to ensure it was working.

Numerous builders install an inverter that powers the 110 volt equipment, ie, a battery charger or the charger side of the inverter charges the batteries from the shore power or generator power and then back from the batteries through the inverter to the equipment.

Inverter systems usually power refrigeration equipment, maybe a microwave, some if not all 110 volt outlets and the entertainment equipment. Cruising & trawler style yachts use these systems to allow owners shut down in some anchorages.

So what size of pump, is there a reqirement that states for a certain volume of space there should be a certain size of pump, not that I can find. The only thing I found after a quick search was "an adequate size pump for normal marine conditions" to be installed.

How many yachts come with an emergency suction on the main engine sea water intakes but nobody has tried opening the gate valves, yes gate valves.

Has anybody seen the 2 1/2" discharge on the very large bilge pump installed in the 34' Luhrs, why ?, cockpit scupper sizes is one reason, aft cockpit drain and low freeboard at the transom gate were but a few issues.

A quick look in the Lewis catalogue and one can see not only 110 volt submersible bilge pumps but also 110 volt submersible air conditioning sea water pumps.

Probably in normal use the capacity of the bilge system on the Nordhavn's is adequate, I would have to ask who would want to go into a flooding Hatteras engine room and find the emergency suction valve if they knew were it was in the first place or look and try and get your hand down to the valve below a Cat' engine in an Alaskan.

I think the problems would be very different if much more time and effort was put into bilge alarm systems. A big bright light and an even bigger audible alarm may help on the outside and alert system thru' the phone, internet, satellite (something like the Magellan system is excellent).

[BEAU]

As a very intelligent someone, said: "Hubris Attracts Nemesis."

Another dumb question from CSH,NY, what does that mean in the context of improperly installed tuna tubes (been using that newly discovered term all day!)??

[Capt J]

Originally Posted by carelm

As I understand it, they are used to keep bait fish alive while big-game fishing.

Here is a site that has information on building your own.

http://www.floridasportsman.com/gear/G_9702_Bait/

That is correct. They look like a very large rod holder, and usually there are several of them, and you have a constant water flow from the bottom up and it flows out of the top. You stick you're baits (live) head first in there and it keeps them alive and you can pull the bait out and toss it to a billfish (or whatever).

They're generally used on boats that tease the fish up and then pitch a bait and yank the teaser away from it.

[travler]

WOW I LEARNED SOMTHING NEW AS WELL what happened to bait tanks or tuna tubes used for the tuna or just the bait or both mabay some one could explain it too those fo us that don't know

curious travler

[Hattsoff]

Originally Posted by Yachtjocky

How many yachts come with an emergency suction on the main engine sea water intakes but nobody has tried opening the gate valves, yes gate valves.

Are what you described above also what (I think) are called crash valves?

[K1W1]

Originally Posted by Yachtjocky

How many yachts come with an emergency suction on the main engine sea water intakes but nobody has tried opening the gate valves, yes gate valves.

Hi,

You mean these things? http://www.yachtsurvey.com/boatreviews/Viking43-6.JPG

I would say that if the Gate Valves were not swung regularly , you would be very lucky in an emergency to get them open at the first attempt.

One thing to be very carefully considered with this system is the need to make sure the strainers used to protect the engine are correctly sized to make sure there is no fouling of the coolers. The newer CATS with Plate Coolers have very small orifices and the Main Sea Strainers need to have a 2.5mm mesh, the emergency bilge suction should be no more than this.

It should also be noted that if using this sort of suction in an emergency it is very important that an eye is kept on it so when it starts sucking air the suction can be flipped back to Sea Water to protect the pump against dry running and or a potential loss of prime.

[Capt J]

Originally Posted by K1W1

Hi,

You mean these things? http://www.yachtsurvey.com/boatreviews/Viking43-6.JPG

I would say that if the Gate Valves were not swung regularly , you would be very lucky in an emergency to get them open at the first attempt.

One thing to be very carefully considered with this system is the need to make sure the strainers used to protect the engine are correctly sized to make sure there is no fouling of the coolers. The newer CATS with Plate Coolers have very small orifices and the Main Sea Strainers need to have a 2.5mm mesh, the emergency bilge suction should be no more than this.

It should also be noted that if using this sort of suction in an emergency it is very important that an eye is kept on it so when it starts sucking air the suction can be flipped back to Sea Water to protect the pump against dry running and or a potential loss of prime.

On the smaller yachts, most of these never get worked and are frozen from what I've seen. The large seacocks are stiff to begin with and the seacock that is designed to be used as the crash pump/emergency pump is exposed to air instead of being immersed in seawater and only a small percentage of owners actually work them every month or two.

The problem I'm seeing with the whole bilge setup on this Nordhaven, is yeah it may have proper bilge pump capacity when the yacht is properly manned via the engine driven pump and valves. But, a 75' can go either way. A lot of 75' don't have any full time crew on them, a lot are owner/operators these days. Also a lot of 75' are left un-attended for days if not weeks at a time, not the most logical thing but it happens. It seems to me Nordhaven is relying on someone to be on board. I'd personally rather see, a lot more pumping capacity in automatic bilge pumps that are DC powered straight to the batteries in a traditional yacht setup, not megayacht setup.

A perfect example was I was unloading another yacht off of a ship about a year or two ago, and the loadmaster asked if I could get everything started and assist these owner operators in a 70-80' Nordhaven that was stuck on the side of the ship. I got on-board and the owner (who only owned the boat for a few months from conversation) was afraid to start the engines and generators "because it had a seachest and since the seachest was drained, everything had to be primed first". I took one look at the seachest which had a plexiglass lid, it was vented and full of water to the top. I told him nothing needed to be primed and started everything, and off they went after they'd been in the ships way for 2 hours. They really were out of their experience level on this size yacht, in every aspect. But unfortunately, I've been seeing way too much of that lately.

As for the tuna tubes. They're setup like a livewell. You have a livewell pump with a thru-hull (in this case 2") that constantly pumps water into the bottom of the tubes, and the water drains out of the top and falls overboard. I'm guessing the hose fell off of the seacock or pump.

[Alaskanmutt]

If I read it right, you cannot keep a small tuna (12 plus inches, bait size plus) in a live well. They will bang around and damage them, lose scales, etc. The tuna tubes keep them calm by using fresh water and the dark (the tubes are black inside)

Originally Posted by travler

WOW I LEARNED SOMTHING NEW AS WELL what happened to bait tanks or tuna tubes used for the tuna or just the bait or both mabay some one could explain it too those fo us that don't know

curious travler

[Yachtjocky]

Hi K1W1,

The most sucessfull sport fishing boat builder over the last 10 years does not use strainers and replies on the external sea water screens which I can assure you have much bigger than 2.5mm openings and many of those boats have the Cats.

As for the bilge pumping capacity, Sea Ray's get a pretty poor rap however each compartment usually comes with a auto switch that operates one pump and then another "Hi Level" automatic switch that both sounds an alarm and also operates a second pump in the same location as the first pump.

[Capt J]

Originally Posted by Yachtjocky

Hi K1W1,

The most sucessfull sport fishing boat builder over the last 10 years does not use strainers and replies on the external sea water screens which I can assure you have much bigger than 2.5mm openings and many of those boats have the Cats.

As for the bilge pumping capacity, Sea Ray's get a pretty poor rap however each compartment usually comes with a auto switch that operates one pump and then another "Hi Level" automatic switch that both sounds an alarm and also operates a second pump in the same location as the first pump.

A lot of the sportfish builders do not install sea-strainers and rely on the screens, it saves them a lot of expense and they rely on the external seawater screens. However, the screens do not filter out sand if your docking in and stirring up sand in a lot of shallow water slips like these sportfish see fishing in Bahamas, central america and such. The seastrainers actually allow a lot of the sand to drop out when the water swirls through it saving the raw water pump impellors. I see about 50% of these sportfish have seastrainers added after the purchase.

[Yachtjocky]

If you were to ask that most sucessful sport fishing boat builder why his boats do not have sea water strainers you would find his answer has absolutely nothing to do with expense at all.

You will also find that very very few of his boats have ever been retro-fitted with sea water strainers and you see them in all parts of the world in both shallow and deep water. Very rarely do I have to clean out sand from a sea water strainer.

[Capt J]

Originally Posted by Yachtjocky

If you were to ask that most sucessful sport fishing boat builder why his boats do not have sea water strainers you would find his answer has absolutely nothing to do with expense at all.

You will also find that very very few of his boats have ever been retro-fitted with sea water strainers and you see them in all parts of the world in both shallow and deep water. Very rarely do I have to clean out sand from a sea water strainer.

Who exactly is the most successful Sportfish boat builder?

If the boat has plates and a seachest instead of the thru-hull directly going into the engine raw water pump, sand will settle out in the seachest and then fall back out when the boat is sitting and bouncing around and such.

There are some valid reasons not to have sea-strainers, one is that when they are mounted on a stringer (which they often are) they can transmit engine vibration to the stringers which then travels through the boat. As well as weight (negligable IMO), engine room space, and a source of possible water leaks

BUT, most of the SF I see in Central America have them, and sand is the reason why. The water swirling in the sea-strainer allows the sand to drop out of it. The plates do nothing for keeping stirred up sand from getting sucked in. They do effectively block enough debris IMO. I know of another Capt. in Mexico that would go through impellors on C18's every 3 months on a big hatteras until he added them. There is little if any tide in most places on the Atlantic side of Central America and a lot of the bigger boats are stuck docking in places with less then 1' under the keel.

We ate a raw water pump at 80hrs on the 45' Cabo I ran in Belize because a piece of sand ate the shaft seal. We added sea-strainers and never had an issue since. There was one place I had to run about 300 yards at 31 knots with .6-.8ft on the depth finder to get through there, it was either that or add 50 miles to the trip and the owner insisted on going that way. Where we docked we had to have his 37' Panga tow us 1.5 miles to his dock because it was too shallow to run the boat in there, and 8 guys to pull it the last 50' alongside the dock. I'd leave the motors idling to keep the shafts cool.

[BEAU]

Karl

Just a by-stander here, but holy cow, this thread has lost it relevance???

[K1W1]

Originally Posted by Capt J

I know of another Capt. in Mexico that would go through impellors on C18's every 3 months on a big hatteras until he added them. .

Hi,

Is that a Jabsco type flexible impeller pump on those C 18's?

[Yachtjocky]

Originally Posted by Capt J

The seastrainers actually allow a lot of the sand to drop out when the water swirls through it saving the raw water pump impellors. I see about 50% of these sportfish have seastrainers added after the purchase.

Is it the "seastrainers" that you refer to in the above that stop the sand or is it the "sea chests" that you refer to in your next post.

Transmitting vibration through sea strainers, flexible rubber hose may help ?