Fifty Feet of Grey (steel)

[Robg71]

yours truly with a welding stinger

ps… dont weld with a Rolex on…. Mine goes backwards….

 

[Robg71]

just for you Vas
pictures above…

street level water supply i would expect more than ten metres as JFM suggest. 10m equals 1 bar (close enough). My domestic boiler at home has a four bar regulator as pressure is 6 bar mains. Not sure what med ports are like, but would expect more than 1 bar pressure.

we have covered lots of ground today. more discussions tomorrow, then need to go to southampton next week for more discussions with various suppliers etc…

 

[Robg71]

the steel work has done together very well. the yard are actually impressed. we have some parts missing, and some parts not rolled or formed, but we can deal with this.
overall, the fit is excellent, with no hammers or ten ton jacks in sight

You chaps have given me some great ideas and food for thought. please, keep throwing them out… no such thing as thread drift on here. its all very welcome dialogue.
we have finalised the mooring and anchoring system, or at least the majority of it. Trying to get all metal work to a point where we now exactly what is going where and how. If it needs cutting, modifying, or changing, this is what we are doing. placement of services involving steel work, such as through hull fittings, shore power boxes etc…
my head hurts, and its not through beer...

 

[rbcoomer]

Cracking job there and amazing progress - well worth the wait over winter! :encouragement:

 

[vas]

Rob,

thanks very much for the pics. Looks quite large for a 50footer!

Care to explain what are these 3 white spots on the transom?
Is it burnt out red primer due to welding/heating from inside?

cheers

V.

 

[Robg71]

from a catch all bracket, when they lined up the side sheet… its great, you can glue bits on to help, then grind em off when finished with

 

[longjohnsilver]

Amazing progress. How long are you spending in Wales and how often are you planning on being there to check on progress?

 

[Robg71]

Cracking job there and amazing progress - well worth the wait over winter! :encouragement:

Thanks Robin, we are getting there.. Thanks all actually

Amazing progress. How long are you spending in Wales and how often are you planning on being there to check on progress?

I am here all day tomorrow, then work from home for a bit, (or Jersey/Guernsey) be back here again next week. meeting the team in southampton next week as well, talks with suppliers etc etc…

these chaps don't need me sitting here babysitting… they know what their doing, and I trust them. can't say fairer than that

 

[vas]

ps… dont weld with a Rolex on…. Mine goes backwards….

ah, don't use a hammer and chisel either on a mechanical one, my Omega started loosing 10mins a day after two days work on MiToS last summer. Shock messed up with the minute timing wire spring (they called it steering...) in there as they then explained

 

[Robg71]

Rob,

thanks very much for the pics. Looks quite large for a 50footer!

cheers

V.

erm… its fifty foot large

 

[jfm]

Mmm.... Don't want to teach granny to suck eggs, but the water flow depends also on the hose section, not just on the pressure (leaving aside other factors).
If you're saying that you backflush while the engine is running, I think that the engine pump would suck from both the fresh water hose and the seacock.
IIRC, we discussed that in the thread which I couldn't find (possibly M1 or M2 build, not sure), and agreed that even if the fresh water hose would supply less water than the pump could draw, it would still be enough for flushing.
But of course, if the pump capacity is higher than whatever the hose can supply, with the seacock left open there would be no backflush at all.
Probably also for the genset, but sure enough for your two 32 liters monsters - unless you connect a MUCH bigger fresh water hose to them?
Otoh, I'd rather not leave the fresh water hose open with the engine not running, to avoid any hydraulicking risks (albeit probably small), as you also mentioned.
Sure, such risks would be even smaller with the seacock open, but all considered, another valve would be a cheap insurance, and by sending the whole fresh water flow back through the strainer, also the cleaning is bound to be more effective...
Anyhow, I did say it was just a thought, and that it's a nice setup also as it is....

Yup, makes sense, I see your point. I don't have the data on flow rates but I get your point.

Due to lack of pump flow data, you might remember that in my maths I took the litres per hour of fuel burn in the Cats at slow idle, and calculated the heat generation from burning that fuel. Then I worked out the flow rate of water needed to absorb that heat with a 30deg C rise. I measured my hosepipe flow rate with bucket and stop watch, and computed that the water flow rate would just absorb the heat generation. I therefore concluded it would be perfectly ok to run the engines for a few minutes on a hosepipe, and of course by intuition you can be happy that there is enough water flow to lubricate the pump impellers

Just on the idea of backflushing of weeds, there is a fly in the ointment in that the scooper water pick ups under the hull have those cast bronze grates over them (at least, they do on my boat, but I think that is common. That will probably stop the weed being flushed backwards. Nice idea though!

In those pictures I posted, the Guidi strainers are 1.25inch size as are the bronze water fittings to the gensets. The new valve I have added with the red handle is 1 inch BSP. The Guidi strainers are nice things, Italy's finest, made in cast bronze and nickel plated, but they are a crazy price

Anyway, fabulous progress on the hull Rob. Thanks for the pictorial update (and to Jersey diver too)

 

[vas]

Yup, makes sense, I see your point. I don't have the data on flow rates but I get your point.

Due to lack of pump flow data, you might remember that in my maths I took the litres per hour of fuel burn in the Cats at slow idle, and calculated the heat generation from burning that fuel. Then I worked out the flow rate of water needed to absorb that heat with a 30deg C rise. I measured my hosepipe flow rate with bucket and stop watch, and computed that the water flow rate would just absorb the heat generation. I therefore concluded it would be perfectly ok to run the engines for a few minutes on a hosepipe, and of course by intuition you can be happy that there is enough water flow to lubricate the pump impellers

J,

sorry for being slightly pedantic, but I guess one can safely assume that the power production is analogous to heat production. However, is that all linear along the rev range? so in effect can you do this calc, or due to demand at the higher end of the rev range (which I guess is how the engineers spec the raw water pump) you could have a pump sucking 2 to 3 times more water than needed to dissipate the produced heat at idle speed?

I like your thinking though

In those pictures I posted, the Guidi strainers are 1.25inch size as are the bronze water fittings to the gensets. The new valve I have added with the red handle is 1 inch BSP. The Guidi strainers are nice things, Italy's finest, made in cast bronze and nickel plated, but they are a crazy price

True, hence I only got the 3/4inch for my gen
BTW, if your gens are 3lt and my engines are almost 7lt then one of the two raw water intake systems is overspecified - or at least I hope mine is not underspec! I'm working on the raw water pump intake which is 1.25 so shouldn't be off the mark. Are your gens raw intakes also 1.25?

cheers

V.

 

[jfm]

Hi vas
I took fuel burn directly off the ecu at slow idle so that's a real data item. Then work from there using calorific value of fuel and heat capacity of water. Plus flow rate measured from hosepipe ( which was 15 mm btw; could easily increase)

My gensets are plumbed by cummins onan factory with 1.25 inch raw water intakes. Perhaps over specified. They are 3.3 litre kubota diesels but only make 60 hp or so. Yep, definitely over specified

 

[MapisM]

Just on the idea of backflushing of weeds, there is a fly in the ointment in that the scooper water pick ups under the hull have those cast bronze grates over them (at least, they do on my boat, but I think that is common. That will probably stop the weed being flushed backwards.

Agreed, not necessarily every bit which found its way in would be pushed out by the reverse flow, but maybe enough for a quick fix, waiting for a better strainer cleaning upon arrival.
At least worth trying, if given the chance...

Coming to think of it, there's another case where the backflush could come in handy.
It happened to me just once in decades of boating, so in this sense it's a solution to a problem that (almost) doesn't exist, but more than likely it could have saved me a jump in the water in that occasion.
One plastic bag got grabbed outside those bronze grates which you mention.
Too big to be sucked inside and reach the strainer, but the water flow managed to get it stuck in that position, and it didn't budge after stopping the boat.
Btw, it wasn't easy to understand what happened, because the flow was only partially restricted.
Anyway, long story short, it was sufficient to gently pull it out by hand from the bottom, so I'm pretty sure that the backflush thing could have done its job nicely, in that case....

 

[MapisM]

BTW, if your gens are 3lt and my engines are almost 7lt then one of the two raw water intake systems is overspecified - or at least I hope mine is not underspec! I'm working on the raw water pump intake which is 1.25 so shouldn't be off the mark.

V., just as a FYI, also my 6.6 L engines have 1 1/4 intakes, so I don't think yours are undersized.
And if that's the size of the pump intake, it would be pointless to use bigger piping anyway!

 

[Robg71]

Home again, been a long couple of days. Early start again to jersey. ready for a break, but been a great couple of days.
Progress is coming on in leaps and bounds.

 

[MapisM]

Hang on a minute, folks!

Again on the topic of fresh water flush, on second thought, it popped to my mind that there's a simpler alternative to fitting a second valve, for backflushing the strainer.
Just look at jfm pic below: it's sufficient to fit a T-type 3way valve instead of the plain T connector, without anything else - aside from the gardena fitting on the bottom, of course.
Job done.
Depending on the valve position, on top of the normal sea water flow, you could flush the engines, backflush the strainer, and also close the circuit completely without the need to reach the seacock valve, whose position might be not so convenient.
I'm not sure it's worth changing the setup for someone like jfm who already can flush the engines anyway, but maybe worth a thought for Vas, Rob, or anyone else who is thinking to make it from scratch...

 

[jfm]

I thought of that Mapism but I couldn't find a bronze valve other than those described as " diverter" or "3 way". I think ( but not sure) these allow port 1 to be connected to port 2 or 3. But in this application you need in addition a valve position whereby 2 is connected to 3 and 1 is closed, if you see what I mean, and I couldn't establish that they do that

I'm very happy to be corrected/ enlightened though

1 is hosepipe
2 is genset
3 is seawater strainer
In my thinking above

 

[MapisM]

Yep, I see what you mean, but afaik among 3 way valves the only difference is between the "L" type and the "T" type.
Following your numbering:
L type allows the connection of 3 to either 1 or 2 (hence allowing only 2 operating positions, let's call them A and B)
T type allows 4 operating positions instead:
A/B) connection of 3 to either 1 or 2 (same as L type); in this application, these would correspond to backflush and normal engine operation respectively
C) connection of 3 to both 1 and 2; useless in this application
D) connection of 1 to 2 (with 3 closed); in this application, this would be the engine flushing, with no need to close the seacock
I can't figure what sort of internal shape can have a valve that only allows 1 to be connected to either 2 or 3...?

Anyhow, just to try to clarify, I had a look at the website of a producer which I know, who makes valves also used in chemical plants.
You can see the schematics of T type valve in this page.
Actually, this is a s/steel valve, but I see no reason why it shouldn't be available also in bronze...

http://www.villavalvole.net/PDF/Pagine/D - Sfere/D - Sfera_Parte7.pdf

 

[Robg71]

Had an interesting afternoon at Clements marine.
looking at shafts, props and rudders etc.
Thanks Paul for info/advice etc

more topside hull plates have been fitted, so its really now starting to look like a boat.

should have a box of goodies on there way soon from Osculatti.
fitting their cleats, and also ordered the electrical shore power box, pressurised deck wash fittings and a few other goodies.
the cleats will be set down in to the steel work, as opposed to bolting on top, on a stainless plate. the plate will have a rounded edge to avoided chamfering ropes, or the ropes chamfering paint...