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Author Topic: Water Line  (Read 4140 times)

john54

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Water Line
« on: July 18, 2008, 05:42:23 PM »

hi everyone
 I have just got my first tug. Not really knowing much about them (used to fast electrics) I would like a little bit of a  advice.
 I have not had chance to try her in the Lake yet. But  when I  test floated her  fully loaded with  battery etc  to get the  ballast correct I had about 15% of the propeller out of the water are not too sure whether the back will dig in when she is underway or will I have to put more ballast in the stern as  the lake  is about 20 miles away I would much sooner make sure she is about right  before I try her out  any advice will be much appreciated.
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john54

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Re: Water Line
« Reply #1 on: July 18, 2008, 05:44:16 PM »

Forgot to say pen tip is waterline
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Colin Bishop

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Re: Water Line
« Reply #2 on: July 18, 2008, 05:47:59 PM »

Looking at the picture I'd say that the waterline needs to be somewhere up near the leading edge of the rudder if not higher. Otherwise the prop will just throw a lot of water about and not do very much! Other people on here are tug experts and will be able to give you more precise advice.

Another possible option would be to use a smaller diameter prop!

Colin
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barryfoote

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Re: Water Line
« Reply #3 on: July 18, 2008, 05:51:06 PM »

John,

You need much more weight in her. The water line should be very slightly above the top of the rudder. This may well make her look stern heavy so will need the bow section lowering as well. Try her in the bath, by applying known weights to the stern and bow until youare about right, This way you will know roughly how much weight to add and where..

Barry
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Shipmate60

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Re: Water Line
« Reply #4 on: July 18, 2008, 06:04:31 PM »

Or if you can add another battery, good ballast and of course increases the duration.

Bob
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catengineman

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Re: Water Line
« Reply #5 on: July 18, 2008, 07:43:39 PM »

Hi,  I think you ideal water line would be with the water just at the rudder post penetration, another little tip would be to have it slightly bow up so that when under full power the tug wont bury her nose quite so much.

With your prop out of the water there would be lots of splash some movement and there comes a problem stopping !  full astern will LIFT the rear and that lessens the amount of prop in the water and so that will equal even poorer control.

Sorry to say this but you tug will need to be heavy and as said before removable ballast is some times best to allow ease of launch recovery but then fixed ballast is some times required in the vessels that have poor access

R
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canute

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Re: Water Line
« Reply #6 on: July 18, 2008, 07:57:06 PM »

I also agree that a little more weight would be appropriate. Here is a photo of my tug where I utilized the Billings 'Banckert' hull. Not only is there a large battery but lots of lead inside as well. You will note the water line by the stern of the vessel.
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Tug-Kenny

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Re: Water Line
« Reply #7 on: July 18, 2008, 08:32:18 PM »

Hi John

Perhaps you could let us know the name of your boat, and then someone could show a picture of theirs sailing.  ;) . This would then give an idea of her water line.

Ken
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john54

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Re: Water Line
« Reply #8 on: July 19, 2008, 06:35:00 AM »

Shes named PLAUDIT ex port of London authority 35in x 8in g.r.p hull wooden deck wheelhouse ,Robbe 1000 ,65mm prop.
7a.h 12v s.l.a (on its side) forward of motor the only place it will fit
I could try fitting another one & put them both upright?
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Colin Bishop

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Re: Water Line
« Reply #9 on: July 19, 2008, 09:46:13 AM »

There are a couple of pictures of the original vessel which show the waterline pretty clearly here: http://website.lineone.net/~alanann/plaudit.htm

Colin
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john54

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Re: Water Line
« Reply #10 on: July 19, 2008, 11:41:59 AM »

Shes LOW Not much freeboard :o
Will be stable though.
I dont know working on f/e makeing them lighter now having to add lb's of lead on this one  ::)
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john54

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Re: Water Line
« Reply #11 on: July 19, 2008, 02:01:04 PM »

Think i am close on ballast now O0
She gos just over 8kg all up.
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farrow

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Re: Water Line
« Reply #12 on: July 19, 2008, 02:27:42 PM »

Nice model, I remember the lighter tugs in the Thames and Medway areas, real hardworking workhorses .
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john54

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Re: Water Line
« Reply #13 on: July 20, 2008, 12:20:21 PM »

Tryed her this morning O0 Goes nice , Turns Very well , Stays cool , Looks Superb (well i think so anyway)
Just need something to tow now ;) Any ideas gents ? (cheap & easy!) if poss.
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Colin Bishop

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Re: Water Line
« Reply #14 on: July 20, 2008, 12:25:03 PM »

Very nice John.  O0
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canute

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Re: Water Line
« Reply #15 on: July 20, 2008, 02:10:02 PM »

John, excellent work. Looks great in the water.
Kim
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john54

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Re: Water Line
« Reply #16 on: July 20, 2008, 03:16:43 PM »

 Thank you for  the nice comments.  I wish  had done this earlier I found her very relaxing to operate no worries about speeding up and down the lake (@ 40ish m.p.h) worried stupid about radio glitches, Things blowing up etc. I'm extremely pleased with her she does not let in one drop of water the only pitfall is taking her in and out of the water especially when the level is low like it was this morning. All she needs now is a job to do ?
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Shipmate60

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Re: Water Line
« Reply #17 on: July 20, 2008, 05:37:41 PM »

Barges are very simple and quick to produce and ballast can be supplied with concrete!!
But obviously will be heavy to launch and recover!!

Bob
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canute

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Re: Water Line
« Reply #18 on: July 21, 2008, 02:58:58 AM »

I'm not familiar with the construction but in our club the barge ballast is water. Holes in the bottom of the barge let a certain amount of ballast water in which adds weight to the barge. The barge is light to transport but yes, a little heavy to drag out of the water if a straight lift is required until the water drains out. This might be discussed in more detail in another section. A barge sure adds more interest and fun if your running tugs.
Kim
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Shipmate60

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Re: Water Line
« Reply #19 on: July 21, 2008, 09:03:28 AM »

One problem with letting water flood into the barge is that it doesnt actually add weight by free flooding.
The effect in the water is nil.
I made up a barge overnight and half filed it with cement, it is still in use now, over 10 yrs since I made it!!

Bob
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canute

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Re: Water Line
« Reply #20 on: July 21, 2008, 03:03:45 PM »

Bob/John, in British Columbia we use 'heavy' water for ballast. Sorry, you probably new that was coming. Actually Bob, one of our club members barges when filled with water for ballast has a tremendous amount of drag. I probably shouldn't use the word 'weight' but 'drag' maybe? Just thought this method would make it easier for transport to and from the pond. At least we both agree that John has a very nice model on the front end of what ever he will be towing.
Kim
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Colin Bishop

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Re: Water Line
« Reply #21 on: July 21, 2008, 03:55:29 PM »

By "drag" I think you mean "inertia". As an example, up in space an object is weightless as there is no gravity. But it still has mass and therefore force is needed to overcome its inertia and cause it to move. If you flood the barge down, you are towing the mass of the water that has entered the hull around the lake which is pretty much the same as saying its weight.

Colin
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