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[bigford]

looking good ian i still think you should have gone 1/50 scale

[boatmadman]

yeah, then I could have sat in her and sailed around!

Trouble is, I would need an HGV to get to the pond!

Ian

[bigford]

i love that pic

[cos918]

looking good Ian . You going to have a working bow thruster.

john

[Umi_Ryuzuki]

looking good Ian . You going to have a working bow thruster.

john

And the two retractable azimuthing thrusters?... 

Looks really nice with the primer coat on!

[Captain Jack]

I don't know about the lingo in the British Navy, but the term Bravo Zulu means "well done" in the US Navy. An awesome looking hull, therefore, a BZ to you sir.

EDIT: I stand corrected, the Royal Navy does indeed use the "Bravo Zulu" flag hoist, as it is used by all NATO forces.

[boatmadman]

A working bow thruster, yes, but not the retractable azimuth thrusters, there isnt enough room in the bows for them. (thats my excuse anyway).

Thanks for the comments folks.

Ian

[cos918]

so is she going to be blue or orange hull

[boatmadman]

Probably orange, but I may change my mind. 

[Umi_Ryuzuki]

Red works also... but it wouldn't be a dockwise ship...
 
http://www.fas.org/man/dod-101/sys/ship/takr-9025-strongvirginian.jpg

plenty of styles and color to choose from...

(my favorite image site,... but do not repost any images from thier galleries.)
http://www.shipspotting.com/modules/myalbum/viewcat.php?cid=51

[Umi_Ryuzuki]

Was it enough to submerge the deck?
How are you draining the tanks to the point were the pump will attach? 

[bigford]

ian

  can you post a pic from a few feet back so i can see the whole ship ::)
i have a few ideas for dropping below the water

[boatmadman]

Here you go, would love to hear your ideas.

Ian

[DickyD]

Ian how much do all your temporary timbers weigh, or are you assuming the superstructure will offset them ?

[bigford]

i was thinking that if you were to add the two uprights at the back of the boat. you
could add a water tank to the front of the ship higher then the work deck. as
you flood the boat the water would rise up the two towers at the back and the  tank
at the front and under she goes

[DickyD]

Surely you will still need more weight or it will just submerge to the level it is now.

[boatmadman]

Dicky, the temp woodwork doesnt weigh so much, you are prob right that the superstructure will offset those. Yes, thinking about it, I need ballast weight (including hardware etc) to bring it down to near normal water level, then use the tanks to submerge.

Bigford, good ideas, however, due to the lack of space above the rudder, I am thinking of mounting the rudder servo in one of the upright columns at the rear and using the cable in sleeve stuff that fliers use - what is it called anyway?

The space above the rudder, plus a space either side are going to be free flooding as well, so that will help.

Ian

[Umi_Ryuzuki]

Ian,

The hull has finished out beautifully.

I would image that a bit of well placed pieces of heavy ballast would be enough to tip the
balance from floating at the deck line, to a fully submerged deck.
I would reserve the stern ballast tanks for foam floatation to assure that the boat, at
neutral, or slightly negative bouancy stays upright, and doesn't turn turtle.

Aimee

[boatmadman]

Good point Umi 

Think I will fill the spaces with bubble wrap!

Ian

[cos918]

hi there Ian she looking good. have you worked out a way yet of rebalacing her once she picks up another boat.

john

[boatmadman]

John,

I am working on that at the moment, curently sealing up engine room and bow section so I can flood her down to a pick up level and experiment from there - watch this space.

Ian

[Mankster]

This is really a big submarime (I've build a few of those) that doesn't go all the way down. I'd first work out how much you want to lift. Lets say 5kg. I'd then add say 10 kg of lead as low down as possible to keep the centre of gravity low. Keep the waterproof motor areas as small as possible, better still, keep your motor above the waterline by using one of those flexible drives the fast IC guys use. This again will keep your CoG low. Make sue your you have plenty of blue foam in the superstructure and all areas above the high waterline (buoyancy casings at the back). This will save save you toppling over and sinkinging if you lift an uneven load or your load rolls over. So if you have set a max lift of 5kg then you will only need 5litres of pumpable ballast (go for a bit more, 8-10l litres, to ballance for an uneven load). The rest of the hull can be free flooding to keep the weight of the model down. As for ballance tank placement, I'd go for 4 individual tanks (each tank with baffles to prevent sloshing about of water) - fore/aft and port/ starboard. This will allow you to trim for an uneven load. I'd use  gyro or, even cheaper, a submarine pitch controller connected to the 4 pumps to effect a level lift (you can switch it off for a manual lift). Alternativle use a shifting weigh for fore/after trim. The ballast tanks obviously need to be vented by a breather tube to some point above the waterline. For final ballasting,  place your finished hull in the water with your 5kg load on deck, and pumpable ballast tanks full. Hopefully Blue Marlin will be resting below the heavy waterline but held afloat by all the saftey foam in the superstructure. Now add more blue foam, just below the heavy water line ( at the port and starboard sides rather than central to maintain stability) till she floats at the heavy water line. Should you find her too tender, just add more lead to bottom and more blue foam just below the heavy load line to counter. Now pumping out your ballast tanks will lift your 5kg load out of the water  :)

[boatmadman]

Thanks for that mankster. I had pretty much come to similar conclusions myself - though a lot slower!

I have 4 ballast tanks and 4 individual pumps. I had intended to flood her until all tanks are full, then add lead to get to the heavy load draft.

Question: Now add more blue foam, just below the heavy water line ( at the port and starboard sides rather than central to maintain stability..do you mean inside the water tanks or in the ballast areas?

Cheers

Ian

[boatmadman]

Mankster,

Tell me more about these pitch controllers please. How many radio channels required, are switchers required, can the pumps run in both directions with these ...etc

These questions prob sound v basic to a subby, but this is my first venture under the water - snorkeling rather that diving 

[Mankster]

Personally I would design the ballast tanks to be as small as possible (just enough to lift your max load). This will mean quicker filling and emptying time. If you want to trim with foam you will need to have a free flooding hull with some parts of the inside of your hull allowing the ouside water to enter and drain through holes in the bottom of your hull. This method will save you about at least 15 kg of lead for a boat this size which you would other wise have to carry around, as well as providing greater stabilty. In model submarine terms, this would be a wet hull submarine rather that a dry hull. If your doing it this way then you need to add the foam in the free flooding part of the hull (stuck on to the port/starboard sides of the hull will give maximum anti roll stabilty. As your deck is going to be below the watersurface to take on the load you don't need to worry about making it water tight either if you do it this way. This is how the 1:1 Blue Marlin works. The alternative is a completely dry hull, ie water is only permitted into your pumped ballast tanks, the rest of the hull, including the top deck is sealed and water tight. You now have so much buoyancy you need to add a ton of lead to get it to the water line. Ok if it is a small model, back breaking if its large like yours.

Plenty of ways to hook up the pitch controller. For port/ starboard ballast tanks, I would have 1 reversible pump going into each tank connected to a single channel on the rx. So a fill command causes both pumps to fill at the same rate. I would add a pitch controller to a reverible esc connected to a third pump that will pump water between the two tanks to maintain a level trim. This pitch controller does not need to be connected to the rx and take up a channel. It is totally autonomus. You have the option to hook the pitch controller to the rx to give you manual control if you need it (you may want want to pitch the boat over to one side so the load slips off the deck). Allternatively you could have 1 cental ballast tank and 2 trim tanks Port and starboard (as well as for and aft ). The trim tanks start off half full of water and a pitch controller connected to a reversible esc connected to a reversible pump shifts water between the two to maintain trim, whilst the central ballast tank purely take the boat up and down.
This is pretty much standard in large model subs - either 2 ballast tanks for and aft to take the sub down and then shift water between the two to maintain horizontal trim; or 1 centrally placed ballast tank and two trim tanks for and after with water shifted between the two to maintain horizontal trilm. With subs we only have to worry about fore/aft trim. With your load carrying sub you need port /starboard trim as well - otherwise it is pretty much like trimming and ballasting a sub.