Nordhavn Expedition Yacht Fish 75 Sinks?

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.

travlr

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)

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.

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.

Karl

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

Hi,

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

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 ?

So what is the reason? Because after cleaning out more than a few engine coolers on boats that have no strainers just hull mounted shoes but no sea chest on them I can't set the point of not installing them other than so save space or money.

He told me that he was on his first or second boat and the strainer filled up with very fine grass and it overheated the engine whereas the other engine was missing the strainer element and the pump sucked but also pumped the grass thru' and that engine did not have a problem.

He also told me why none of his boats he built ever come with large 8D batteries but that is another story.....

PS. I am not about to argue with him due to his success but I would install both the external strainers and the internal strainers and definately sea chests if space allowed

Yes. I think Sherwood manufactures the pump, but it may be Jabsco.

Both seachests and sea-strainers will allow a decent portion of the sand to drop out of the raw water. The swirling effect of the sea-strainer as it goes through the basket area allows the sand (heavier then water) to drop out to a degree.

Sea-strainers have the same effect as the thru-hull is feeding a large box, and as the water goes through the large box, some of the sand drops out in the box, well with the thru-hull or thru-hulls located in the bottom of the box, when the engines are not running gravity allows it to fall back out.

Wire-bound flexible hose is usually always used going from the thru-hull to sea-strainer, and sea-strainer to engine. however 2"-4" I.D. wire bound hose is pretty stiff and the hose runs are typically short in a sportfish(a few feet or less) so it does transmit a good portion of this vibration to the sea-strainer which is usually rigidly mounted on a stringer.

CaptJ, do you want to edit the above before anybody corrects it for you.

Hi,

There seems to be some confusion here with the terminology being bandied about.

Sea Chest: The sea chest is a rectangular recess in the hull of a vessel that provides an intake reservoir from which piping systems draw raw water. Most sea chests are protected by removable gratings and contain baffle plates to dampen the effects of vessel speed or sea state.

Sea Strainer or Mud Box: A sea strainer is designed to filter contaminants out of seawater for seafaring engines. A good sea strainer will remove pollutants such as algae, bits of aquatic vegetation, man-made debris, leaves or rocks, and even small fish and other creatures that may have gotten swept into the system. Many people choose to install sea strainers to improve the overall quality of their boat engine systems, helping the engines to last longer and perform at peak efficiency.

Read more: Sea Strainer Installation | eHow.com http://www.ehow.com/way_5860058_sea-strainer-installation.html#ixzz1EK13jJOL

wondering where "mud box" appeared in that link you posted.

External sea water screen, is mounted on the "external" area of the hull and usually comes with a removable screen. This screen can be mounted for a sea chest or over a regular sea water thru' hull fitting.

Sea Chest, can be any shape and not just rectangular (alot of very large ones are circular to help in cleaning and the very very large ones are part of the double bottoms of ships). They usually come with a gasketed top hatch that on smaller ones is usually a clear type of plastic. There is a vent on top of the hatch and this hatch is bolted (cheap & dangerous ones are screwed). Good sea chests also come with a finer strainer installed on the inside.

There are any number of sea water outlets from the sea chest that should have a good quality valve mounted on the outlet pipe or flange.

A sea water strainer is usually mounted either directly on the thru' hull fitting or is connected to the thru' hull fitting / valve by flexible suction hose and then is connected to the engine sea water pump by the same flexible suction hose.

Due to the nature of the hose there is very little vibration passed from the engine to the stringers through a strainer (!)

The sea strainer usually has a very fine strainer material and a plastic type bowl or top that one can see if there is a build up of debris in it (very difficut to see after a few months)

Very rare to find a vent on top of these internal strainers and that is why the engines, generators and air conditioning pumps quiet often loose suction after being hauled ashore. it is a good idea to close the thru' hull valves when sea strainers are installed before a vessel hauled ashore.

Some boats come with a molded in sea chest that only has a screen on the external area of the hull and no screen and no way to open the chest from the inside. They still come with a vent though.

Scoop type external screens should face aft when installed for generators as water can be forced into the cylinders if running and generator is off.

If external screens are used they have to have their own zinc or bonded by a thru' hull bolt. Sea chests often have bronze external screens and stainless steel internal strainers that tend to corroded rapidly.

Anybody with an earlier model of the IPS will find that they have sea water ingress issues as the sea water strainer is plastic and is (was) mounted on the "pressure side" of the sea water pump. At 93% load the pressure is too much and the top leaks badly spraying the water around on the port alternater and all engine mounts.

Back to bilge pumps, another method was to use a venturi which ran continuously when the vessel was in use and another idea that is being marketed these days is like a central vacuum (I think it is called a WillyVac) that can be used to empty out any compartment and dump into a container.

Neither would have helped the Nordhavn but.....

Having a large DC voltage pump would not be a good idea either as the power used each time it came on and off would drain a battery bank. Like I wrote yesterday about the Sea Ray's, a good pump and automatic float switch for normal use and then another float switch to activate a larger pump and an even bigger alarm would be the way to go IMO. Why put a large pump in for normal everyday use.

It doesn't appear in that link to the best of my knowledge, I just added it in as it is something that strainers are sometimes referred to as even though the normally accepted use of a traditional one is as a Bilge Suction Strainer on ship.

That is not a problem restricted to IPS Boats alone, many VOLVO Engines use this system. If it doesn't leak it does have one pretty good saving grace IMO - Wanna take a guess what it is?

This type of thing is still used on jet boats and the like, there is also the venerable Bilge Eductor in use on many vessels as well as an OWS.

When in Sweden they explained it was only to save space (saving grace, I thought you were telling me the answer as you asked it).

They built those VP's to just slide into the spaces that they called machinery rooms back them, had to remove an engine to change a starter motor.

Bilge Wells around the world and mud boxes in the USA. (soccer & football)

Hi,

The answer I was after is they are a great place to find the blades that have come off the Impeller before they get to the coolers.

Personally I hate those plastic things Volvo use apart from what I just wrote.