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[J.beazley]

I shall be following this build with keen interest, tried it didnt work smashed the thing to bits end of story.

heres a link to a LARGER on that may be of some use if you havent seen it before in your research.
http://www.scheepsmodelbouw.ismijnhobby.nl/

good luck with the build

Jay

[boatmadman]

Jay,

Could you tell me what problems you had?

Ian

[cos918]

hi Ian your a brave man as that one mean feat of model boat headache.
I have often though about building one of these boat but could never get my head a round how to get the ballast system to work. To get the boat to go up and down with no cargo is not to hard as it the same as a sub. But when she lifts and picks up another boat all the trim is out and needs compensating . Its this i could never work out . It would be nice to hear your ideas . All the best cant wait for the next up date.

john

[boatmadman]

Well, at the moment I have the idea of 4 seperate ballast tanks and pumps, so I should (hopeful!) be able to adjust the trim. The water tanks look at the moment as though they will hold about 21 litresl of water.

Physical location of the gear is something I havent sorted yet!

Ian

[J.beazley]

I had problems when i tried to get the water into the milk cartons i was using in the hull, the hull rolled to one side everytime i tried to get her submerged which is probably why i got annoyed and bined it.

The only other thing i recall was trying to get the hull submerged with just the water, didnt work as i was just effectivly adding water to the inside of the hull which didnt change the overall ballast of the hull.

Hope this is of some help

Jay

[cos918]

21 litre of water . Should get good lift from that amount of ballast. When I look at it i worked out that you want ballast tank full of water for full submerge about or no more than  30% for normal sailing, and totally empty for lifting  to gain extra lift. So at 21 litre tank you could lift about 12kg model . Make sure you ballast tanks are baffled to stop water sloshing a round.
I thought of 1 or 2 main lift tanks and about 4 small trim tanks around the boat best one each corner.

john

[boatmadman]

John,

I was working on a lift of about 10kg, and, yes, I also reckoned about 1/4 to 1/3 full for normal running.

Baffling the tanks - yes I am aware of the need for that to minimise the free surface effect.

The reason I am thinking of 4 tanks at the moment is that I am unsure just how much space for pumps i will have, bearing in mind the rear section will have to be for drive units only.

Ian

[bigford]

ian
 heres a fellow who built one, i think it german or dutch
http://www.wk-e.de/Mighty%20Servant%203.html
and my fav

[boatmadman]

Bigford,
Thanks for that, I hadnt seen those pics before.

Ian

[Umi_Ryuzuki]

Here's another link that I Keep handy...

http://www.wk-e.de/Mighty%20Servant%203.html

The data I recieved was for the MS-3 and the SS-3.

Are you doing the original hull, or the extended and widened hull for the Blue Marlin?
 :)

[boatmadman]

Hi,
I am doing the widened hull version.

Due to the scale I am working at I am having difficulty getting the stern right below the waterline, I may have to modify to make it possible to model.

Ian

[Umi_Ryuzuki]

If the stern is something like the MS-3...
Perhaps you can build up the stern smooth, and the fair in the propeller skegs.

[cos918]

hi Ian
I have been giving your model some though to day while driving to an from work.
1 let say you have a rectangle or a hull and 4 tanks on in each corner of 5L capacity each and 4 pumps. The vessel will go up and down on an even keel. OK now let add a bow and put in the recess of the stern we now have the vessel more buoyant to the bow. So we increase the bow tanks to say 6L or 7L and reduce the stern to 4L or 3L. The stern tanks will fill quicker than the bow causing the vessel to sink stern first, not the disired result. So remove 3 pumps use one pump and connect all 4 tanks with say 10mm dia pipe. This will allow all 4 tanks to fill evenly causing level sinking.

2 say you go to lift a 12kg model boat but she not on square to you central lifting point. Say she was over to port and a bit aft of centre . As you lift the rear port of you vessel would be lower and the front starboard would be up. To compensat if you wear using 4 tanks and 4 pumps you would need to put more water in the forward starboard tank. Then the % of extra weight in that tank would have to be maintained to keep you vessel level during the lift. This could be hard to achieve.

one way is to have the 4 linked tanks as lift only. Then you could put in trim tanks this is could be a lot of work. Or what you could do and i have seen done on a diffrent vessel. Is to have a thread bar that runs across the centre of the ship and on this bar there is say 1 kg weight. as the bar turns the weight moves to port or starboard depending on rotation . All so have the same bar for forward to aft. So when you star to lift you move the weight to re balance your boat. The beauty of this system over trim tanks is 1 you don't increase the weight of your boat and 2 it more controlable than moving water.

john

[Adam]

hi Ian
I have been giving your model some though to day while driving to an from work.
1 let say you have a rectangle or a hull and 4 tanks on in each corner of 5L capacity each and 4 pumps. The vessel will go up and down on an even keel. OK now let add a bow and put in the recess of the stern we now have the vessel more buoyant to the bow. So we increase the bow tanks to say 6L or 7L and reduce the stern to 4L or 3L. The stern tanks will fill quicker than the bow causing the vessel to sink stern first, not the disired result. So remove 3 pumps use one pump and connect all 4 tanks with say 10mm dia pipe. This will allow all 4 tanks to fill evenly causing level sinking.

You have to do a lot of driving home John, because this will not work.
You can never get four tanks to fill exactly the same.
Due to internal friction one tank will always fill quicker than the other one.
Look at the lay out of the ballast tanks of the original ships.
There aren’t that many tanks for no reason.
If it was as simple as you suggest, than they would build it like this in the big ships too.
That way the ships could be build a lot cheaper.

By the way, the original ships will sink stern first most of the time

[boatmadman]

Umi,

I am already working on lines of what you suggest, developing my own stern lines faired into a single prop - the real Blue Marlin is a single prop.

John, thanks for the thoughts, interesting concept but i think its not practicable, the weight needed to be moved around would probably be too great, plus actually finding a place to fit it! At 1:175 I am surprisingly limited to space.

Adam, I agree with your comments, at the moment I am working on the concept of 4 tanks and 4 pumps, inidividually controlled. I will see how this works when I eventually get to the test tank stage. I am working on the idea of having a removeable deck, so I can test with the deck off, and modify as required.

Ian

[tigertiger]

Let me start by saying I know nothing. But I have a couple of thoughts none the less.

I think the problem with differeing friction in the tanks could be minimised if the tanks were filled slowly.
With 10mm pipe between 5 Ltr tanks I don't see too much of an issue. That is a relativley fat cross section of pipe.

I imagine you may need to considet the distribution of the weight of water in the pipe as well.

If you used a two way pump then the water could also be pumped out slowly and I think she should come up fairly evenly. This way you would not need to tip the boat, just pick her up when the tanks are empty.

I can see that there may be a difference in bouyancy between fore and aft. But little issue port and starboard.

Perhaps 2 pumps. one for the two forward tanks (linked by a 10mm tube). A second pump for the two aft tanks (also connected to each other). The forward and aft tanks are not connected. With two pumps you can trim her as the tanks fill. Perhaps you could even use a mixer.

Just some initial thoughts.

[tigertiger]

One other thought.

With four tanks (not connected) and four pumps.
You will be able to trim the ship to allow for picking up a load where the weight distribution is uneaven, of off centre.

This will take a lot longer to operate, but I am sure this is not done quickly with the real ship.

[cos918]

hi Ian
I have been giving your model some though to day while driving to an from work.
1 let say you have a rectangle or a hull and 4 tanks on in each corner of 5L capacity each and 4 pumps. The vessel will go up and down on an even keel. OK now let add a bow and put in the recess of the stern we now have the vessel more buoyant to the bow. So we increase the bow tanks to say 6L or 7L and reduce the stern to 4L or 3L. The stern tanks will fill quicker than the bow causing the vessel to sink stern first, not the disired result. So remove 3 pumps use one pump and connect all 4 tanks with say 10mm dia pipe. This will allow all 4 tanks to fill evenly causing level sinking.

You have to do a lot of driving home John, because this will not work.
You can never get four tanks to fill exactly the same.
Due to internal friction one tank will always fill quicker than the other one.
Look at the lay out of the ballast tanks of the original ships.
There aren’t that many tanks for no reason.
If it was as simple as you suggest, than they would build it like this in the big ships too.
That way the ships could be build a lot cheaper.

By the way, the original ships will sink stern first most of the time

hi adam yer a hell of a lot just a mear 240 miles to day
so on the rear ship how many tanks do the have and to they have separate trim tanks.

john

[boatmadman]

I tend to agree about the pipe friction TT, I was thinking in the region of 6 to 10mm pipe and two way pumps, as used in model subs. These pumps are rated about 1 to 2 litres a min. giving a somewhat realist ballast/deballast time.

The 4 tank idea was to try and allow compensation for out of centre loads as she rises, just as you say TT.

Keep am coming Lads - good discussion.

Ian

[tigertiger]

Thinking completley out of the box now.
Seeing as you are probably going to need many channels for your radio. Pumps and all the usual stuff. Bow and stern thrusters as well no doubt.

Why not get one of those fancy radios wot does telemetry.

Then you can have a micro camera at each end, looking into the centre, so you can see how you are positionin yourself for a 'lift' from a more remote position. So maybe from the other side of the lake you can wow the crowds.

I don't know how this is done, but lost of video on Youtube of boats and planes with these cameras on board

[cos918]

Ian on sub as i have 3 . The pumps (car windscreen type ) cant hold pressure. IE water will seep past them. So if the pumps were mounted in the rear funnel i think above the flood deck this should get a round this problem.

john

[Martin (Admin)]

How are you going to protect the woodwork?

[cos918]

hi ian found this photo on the net Know its not your boat but thought it might be of some use.

john

[boatmadman]

Thanks for that John, I hadnt seen those pics.

Ian

[John W E]

hi ya there

One method I have used in the past for planking into tight radius' is to split the plank in the centre - the length of the split is from at least 2 flat frames away from the frame with the radius in; and this prevents the split from running further up the plank when applying it.

Also, if you put a clamp across the end of the split that also helps to prevent it running further up the plank when applying.

Just out of curiosity, what type of wood are you using to plank the hull with?   

aye
john e
bluebird