Boat in build pics (Squadron 78)

[sarabande]

Can I ask about the rationale behind connecting all the tanks together please ?

7200l is about 6 tonnes, and if the tanks are interconnected, that means the fuel will move to a different position when under way from when at rest.

I have no experience of big mobos, other than Grey Funnel ships, but the ability to load into separate tanks, draw from separate tanks, or transfer from one tank to another would seem to be a desirable risk mitigation and good fuel integrity policy ?

Ta!

 

[jfm]

Can I ask about the rationale behind connecting all the tanks together please ?

7200l is about 6 tonnes, and if the tanks are interconnected, that means the fuel will move to a different position when under way from when at rest.

I have no experience of big mobos, other than Grey Funnel ships, but the ability towould seem to be a desirable risk mitigation and good fuel integrity policy ?

Ta!

I'll have complete choice. I can load into separate tanks, draw from separate tanks, return fuel to separate tanks, isolate any tank, or transfer from one tank to another. Each of these choices is made separately for each of the 4 engines. Engine A can draw from tank 1 and retrun to tank 2; engine B can draw from tank 2 and return to tank 3, and so on. There is a schematic diagram of the plumbing, and all valves are reachable and labelled

But I expect for normal use I'll leave the tank interconnect valves open, so creating one virtual tank, and draw from the centre tank, which is the lowest. I might not do that over winter when the boat is standing, so as to reduce static hydrualic pressure in the lowest tank

When running as one virtual tank the fuel will not substantially move to a different postion when underway from when at rest

When the boat rocks with waves the fuel doesn't move appreciably between the tanks becuase the small bore of the interconnect pipes throttles the flow. When the boat rises on the plane and stays there for some time there is a slight aft-wards shift of fuel, from centre tank to the two bigger aft tanks, but the amount is tiny (100kg max, at a guess) and would have no material effect on the boat's weight distribution

 

[Hurricane]

Question on tanks then.

I keep my port tanks isolated from my starboard ones - I have two each side.

I've always assumed that I might get a very undesireable effect if I open the valves between the port and starboard tank sets.

I've assumed that with a part fuel load, it would be possible for a large proportion of fuel to run to one side or the other. As the weight increases on that side, even more fuel would run until the boat was leaning significantly.

Is this a correct assumption. If so, you might want to rethink your "open all valves" strategy.

 

[sarabande]

I thought you would have it under control by design , but with "open valves", you have in effect a free surface effect. This is sometimes considered to be a Bad Thing. It's not going to produce an instantaneous unbalancing (as free surface water on the deck of a carrier or ferry for instance), but could gradually emphasise a heel angle if the boat is on a steady course with a strong side wind for instance. I'm with Hurricane - controlled store, draw, and transfer for ballast purposes as well as fuel integrity is desirable.

 

[Deleted User YDKXO]

Yup, 100% agree. IMHO there is nothing to touch a W'Bay tender in this size range.

Down here in France everyone raves about Novranias. They're quite nice, but a bit utilitarian looking imho. And no UK dealers, so I'd have to buy n France and pay the mental prices down here, then ship it to UK. The Avon 400DL is very nice, and my 2nd choice if for any reason I can't get a W'Bay. But assuming I can get one and based on what I know now, I'll be getting the W'Bay. I think it's by far the best design in this size range and the build quality is excellent

Sizing is tricky and I wish W'Bay made a 4.10. But they only do 3.9 and 4.3. The 430 is a bit big (I can't use the full platform width becuase of the passerelle) though it would fit at a push. But the 390 is perfectly big enough I think, so I think is the better choice, with a Merc or Yam 50, but I'm pondering on it

I inherited a Novurania with my last boat and, yes they are a bit utilitarian, but v well made, certainly better than the Arimar I've bought for my current boat. Agree though that the Walker Bay is a lovely bit of kit

 

[Deleted User YDKXO]

I'm sure you know that Princess have their own little addition to the TankManager system in that they integrate the panel into the boat's DC panel. My fault was that one of the little lamps (LEDs) failed to operate. The fault turned out to be in the master control box but having a complete set of parts made it very easy to find and fix. I also had a failure of the bottom switch on the sender but I'm sure we've all been there!!!

Funny how conversations all end up about holding tanks!!

Ha, thats because, apart from aircon failure, a holding tank system failure is just about the worst thing that can happen on a Med cruise so it will definitely pay jfm to have some redundancy in his system particularly if he's going to charter! Ferretti use all Tecma stuff for the toilets and tank floats/senders along with a very sturdy G & R screw type discharge pump. The Tecma stuff is good quality so I think jfm has done the right thing

 

[jfm]

Question on tanks then.

I keep my port tanks isolated from my starboard ones - I have two each side.

I've always assumed that I might get a very undesireable effect if I open the valves between the port and starboard tank sets.

I've assumed that with a part fuel load, it would be possible for a large proportion of fuel to run to one side or the other. As the weight increases on that side, even more fuel would run until the boat was leaning significantly.

Is this a correct assumption. If so, you might want to rethink your "open all valves" strategy.

Hurric I have run the Sq58s last 7 years with the balance pipe left open, and even when the boat has rocked from side to side in bad conditions the weight transfer (free surface effect) has been isignificant. The balance pipe is effectively shut, for the purposes of the flow rates concerned here and the time period of a boat rocking from side to side. I haven't done the maths but I bet the side to side transfer is way less than 100kg, which is nowt. (One can google the flow rate of a thin fluid through a say 30mm pipe with say a metre and a half of head; I bet 20-30kg of fuel gets through in say 10 seconds, max). Also, I've always filled up through one side only - the flow rate thru the balance pipe (about an inch dia) has been approximately 50% of the fill rate, ie enough to keep things balanced. It has never made the boat lean while filling. So while I see the concern you're raising it isn't an issue in practice imho

 

[jfm]

I thought you would have it under control by design , but with "open valves", you have in effect a free surface effect. This is sometimes considered to be a Bad Thing. It's not going to produce an instantaneous unbalancing (as free surface water on the deck of a carrier or ferry for instance), but could gradually emphasise a heel angle if the boat is on a steady course with a strong side wind for instance. I'm with Hurricane - controlled store, draw, and transfer for ballast purposes as well as fuel integrity is desirable.

But Sarabande you have nothing like a free surface effect when the balance pipes are say 30mm dia. The flow rate you can get through such a pipe is just tiny compared with the flow rate as free water runs across the deck of a commercial ship.

You're right that it would increase the heel angle if you were on a steady course with a side wind but I would always correct the heel with the tabs. I did that often with the Sq58 - adjusted the tabs to eliminate a sideways lean, specifically because I was concsious that if I didn't then the lean would increase due to gradual sideways flow of fuel

I'm not disagreeing on principle. Just saying that in practice for everyday good weahter boating running a single virtual tank makes for a lot of convenience and is fine. In storm conditions, or where you had bad fuel to be isolated, or wanted to transfer weight for a specific reason, then it's time to play with the valves

 

[Hurricane]

Hurric I have run the Sq58s last 7 years with the balance pipe left open, and even when the boat has rocked from side to side in bad conditions the weight transfer (free surface effect) has been isignificant. The balance pipe is effectively shut, for the purposes of the flow rates concerned here and the time period of a boat rocking from side to side. I haven't done the maths but I bet the side to side transfer is way less than 100kg, which is nowt. (One can google the flow rate of a thin fluid through a say 30mm pipe with say a metre and a half of head; I bet 20-30kg of fuel gets through in say 10 seconds, max). Also, I've always filled up through one side only - the flow rate thru the balance pipe (about an inch dia) has been approximately 50% of the fill rate, ie enough to keep things balanced. It has never made the boat lean while filling. So while I see the concern you're raising it isn't an issue in practice imho

Hmmm

I think I'll continue to to keep the balance valves closed and fill both sides independantly.
Apart from that, it gives me an indication if one engine is burning more than the other - although I have to allow for generator usage.

Anyway, apart from refueling, I cant see a benefit so why create a potential problem that may (or may not) be there?

 

[andythilo]

I've got to say, this is an amazing thread and your an incredibly lucky individual to be able to document such a build, let alone own the boat!

One day... one day

 

[benjenbav]

Plus it's great to see someone who has a choice, investing in local manufacture, craftsmanship and skill, with the belief that it's going to produce the best product for the investor's purpose.

 

[Deleted User YDKXO]

Hurric I have run the Sq58s last 7 years with the balance pipe left open, and even when the boat has rocked from side to side in bad conditions the weight transfer (free surface effect) has been isignificant. The balance pipe is effectively shut, for the purposes of the flow rates concerned here and the time period of a boat rocking from side to side. I haven't done the maths but I bet the side to side transfer is way less than 100kg, which is nowt. (One can google the flow rate of a thin fluid through a say 30mm pipe with say a metre and a half of head; I bet 20-30kg of fuel gets through in say 10 seconds, max). Also, I've always filled up through one side only - the flow rate thru the balance pipe (about an inch dia) has been approximately 50% of the fill rate, ie enough to keep things balanced. It has never made the boat lean while filling. So while I see the concern you're raising it isn't an issue in practice imho

I do the same on my boat. I have 3 tanks, two main tanks on port and s/b sides and a smaller 'day tank' aft and I keep the balance pipes open between all of them. There are 3 separate deck fillers but I fill from just one or other main tank filler, whicever is on the side I'm moored. The boat lists a bit on filling but soon settles and the only problem is that its a bit slow to fill because, as you say, the balance pipes cant distribute the fuel fast enough. As for listing whilst under way due to fuel migrating to one tank, I've never noticed it and in any case, on my boat, the main tanks are ahead of the engines and close to the centre line of the boat so any imbalance would be minor.
Anyway, I cannot imagine that the naval architect who designs these hulls does not consider a worst case imbalance situation when analysing the stability of the hull. In any case, shutting off the balance pipe between tanks would not ensure total safety as a major rupture of one fuel tank would lead to a similar imbalance situation as leaving the balance pipes open

 

[Hurricane]

In any case, shutting off the balance pipe between tanks would not ensure total safety as a major rupture of one fuel tank would lead to a similar imbalance situation as leaving the balance pipes open

Good point, Mike, but a bit obtuse meethinks - I could also say that if you rupture a tank you could loose the whole fuel load!!

 

[Deleted User YDKXO]

Good point, Mike, but a bit obtuse meethinks - I could also say that if you rupture a tank you could loose the whole fuel load!!

You could say that but I'm sure jfm will be specifying special solenoid controlled balance pipe valves controlled by sensors which detect sudden changes in tank levels and automatically shut off the balance pipe valves in the event of a tank level change which exceeds a preset amount
I'm sure he'll be along in a minute to confirm this

 

[Bajansailor]

Excellent thread jfm, thank you for posting all the photos so far, and the very useful explanations.
I think that most folk on here would agree that these construction photos of your 78 in build are far more interesting than the glossy photos that one sees in the advertising brochures at the end.
Did you ever do a similar sort of thread re your 58?
If not, could you post some photos of her build (perhaps in a separate thread) sometime please?
I am sure that everybody on here would love to see them, and be told in simple engineering speak how it all went together, if you can set aside some time to compile such a thread.

 

[MapisM]

You're right that it would increase the heel angle if you were on a steady course with a side wind but I would always correct the heel with the tabs.

Naaah, you're not yet used to the idea that you'll have a stabilised vessel, I reckon.
Forget sideways lean, forget tabs correction. You could even fit a single command driving both the Xmas cracker thingies, because their only usage (if any) will be for small adjustments of longitudinal asset, nothing else.
Actually, you could have the opposite problem, because if you forget only one tab fully lowered, you'll have no way to realise that, unless you fit an indicator or you turn the stabs off.

Btw, re. your previous reply, I fully agree that the fins position vs. the lift strips doesn't matter at zero speed, and is probably of very little relevance also while cruising. In fact, the lift strips interferences will only be relevant at higher speeds, where the fins are extremely effective anyway, even with very small movements.
Admittedly, my previous comments were a bit academic, in this respect - but I was just curious.

 

[AndieMac]

I do the same on my boat. I have 3 tanks, two main tanks on port and s/b sides and a smaller 'day tank' aft and I keep the balance pipes open between all of them. There are 3 separate deck fillers but I fill from just one or other main tank filler, whicever is on the side I'm moored. The boat lists a bit on filling but soon settles and the only problem is that its a bit slow to fill because, as you say, the balance pipes cant distribute the fuel fast enough.

Generally at our home berth I fuel the P66 from our own 3000 litre trailer, via extra filters and a 40 litre per minute pump, as you do, into just one side.
With a fairly slow fuel discharge rate of 40 LPM (same as service station pumps) the balance pipe copes very well, and perfect for a single operator to do roving checks on proceedures, but quite slow.
The balance pipe is always open, and is only closed off to check the levels of both tanks on the sight guage on the fwd. bulkhead.

When coastal cruising I use fuel trucks with fast delivery pumps (110 litres per minute), but close off the balance pipe to closely monitor the sight guage to avoid over-flow. Usually put in 2000 litres per side, per fill, out of a possible 2500 litres per tank. Then open up the balance pipe.

 

[jfm]

gives me an indication if one engine is burning more than the other - although I have to allow for generator usage.

The instruments tell you the fuel burn though Hurricane

a potential problem that may (or may not) be there

We can't just ignore the laws of physics! The velocity of a viscosity-less fluid through an oriface is Sq root of 2xgxH where H is the head in metres and g is the usual gravity constant.

So if the boat lean sideways alarmingly, and there is a 2m head difference twixt the levels in the port/starboard tanks, the velocity of flow is Sqroot of 2 x 9.8 x 2 = 6.5 metres per second

I'm being VERY conservative: the friction in the pipe, the viscosity of the fuel, etc, will all reduce the actual value. And 2m head difference is close to capsizing. But let's stick with the 6.5 m/second velocity

6.5 metres per second thru a 30mm dia pipe (cross section area say 1000mm sq) is 6.5 litres per second. Let's say the boat is rolling slowly so it leans one way a full 10 seconds before rocking back the other way. 10 seconds means 65 litres of fuel flows thru the balance pipe. That's say 55 kilos.

That's nowt, (and the real number would be more like 20 kilos)

 

[jfm]

Naaah, you're not yet used to the idea that you'll have a stabilised vessel, I reckon.
Forget sideways lean, forget tabs correction. You could even fit a single command driving both the Xmas cracker thingies, because their only usage (if any) will be for small adjustments of longitudinal asset, nothing else.

Doh!!! Yes of course MapisM, you are right. I wont be using tabs any more to correct sideways lean, and will only ever use them in synch to lower the bow. You are right, I'm not used to the idea of a stabilised boat yet!!

Just as an aside though, this is only true of a fin stabilised boat underway. In a gyro stabilised boat underway, the gyros couldn't correct a sideways lean afaik. Gyros can only resist an unwanted motion, not an unwanted steady-state condition. Agree?

 

[jfm]

I think that most folk on here would agree that these construction photos of your 78 in build are far more interesting than the glossy photos that one sees in the advertising brochures at the end.
Did you ever do a similar sort of thread re your 58?
If not, could you post some photos of her build (perhaps in a separate thread) sometime please?

Hi Bajan.
No, I never saw my last Sq58 in build. It was a dealer stock boat displayed at southampton boat show Sept 2008, which I didn't attend. Then I heard about it, saw it and just bought it on impulse. So i never saw it in build

My earlier (2004) Sq58 was built to order and I did see that in build once, and got some pics. I'll try to find them, but they're not on this pc

The 58 is of course a production boat so the opportnities to get involved in the spec and detailing are limited, compared with the 78 where there is full opportunity to be involved if you want to. I've visited the factory several times, am there again tomorrow, and have exchanged a couple of hundred emails with the design team and given them tens of scale drawings and sketches