Author Topic: Oh God I Need Help! - Images Added  (Read 14070 times)

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freightliner009

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Re: Oh God I Need Help! - Even More Images Added
« Reply #15 on: July 09, 2014, 08:22:27 »
Guys,

I chopped a bit further this afternoon....see new images below, hasn't she been built well?

Anyway I now have some room for manoeuvre but I may go the whole hog and strip all the electronics out and the rest of the compartment....what do you think....I don't want to waste time doing this though if it will make no difference to the buoyancy with the addition of the superstructure?

Shall I cut a window in the front bulkhead to get right into the bow or will this compromise the hull strength?

As far as the existing battery goes I can reduce its height by approx. 35 - 38mm by simply lying it on its side.

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CORONA

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Re: Oh God I Need Help! - Images Added
« Reply #16 on: July 09, 2014, 15:48:30 »
Hi Andy,

Built well is right - shame to tear it out but I think it makes sense. ( my vote )
If you can get the battery down between the frames it would be even better that just on its sides.
I see now the bottom is very round so the balance has to be perfect otherwise it will list (or turn over if COG is not low ) .
You could certainly take out at least 50% of the front bulkhead with out affecting the integrity.
It looks like plywood in the picture so should retain same shape well.
It may give you more options as to how you can place any ballast if you need it too ( on the bottom of front compartment )

Good pictures !!

Laurn

des

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Re: Oh God I Need Help! - Images Added
« Reply #17 on: July 09, 2014, 22:21:24 »
G'day Andy

If your battery is roughly 40mm less high by laying onto its side than standing it upright, then you will reduce the CofG OF THE BATTERY by about half of this.  This will also reduce the CofG OF THE HULL, with battery, by about half again - say about 5mm.  When you add a heavy topsides into the equation, the resulting effect will be less again - probably no more than 1-3mm.  Certainly worthwhile, but not enough I'm afraid.

There's no escaping it mate - that battery, and any additional ballast, needs to go right down into the guts of the hull - right onto the bottom.  (Obviously you'll need to leave some rib material for hull strength.)

Yes, there are all sorts of things you can do with smaller, lighter batteries, different types, and so forth. But your heavy upperworks is also contributing to the overall instability of the model, so to counteract this you must get the rest of the heavy stuff right down into the bottom of the boat.  (Have you fitted your mast yet?  The weight of that, even though usually not much, will also have a destabilising effect due to its height above the Centre of Buoyancy of the boat.)

I would also consider taking the keyhole saw to that forward bulkhead to create an opening to place ballast further forward to bring your bow down, if you can't relocate the battery itself further forward.

Des.


freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #18 on: July 10, 2014, 00:56:21 »
Thanks guys, your advice will be todays work on the tug and I'll report back for your views and further advice.

Am I right in assuming then Des that the more weight in the hull will eventually stabilise the superstructure and if so it's more than likely to compromise the current water line?

Also, placing ballast right in the rounded bottom isn't possible because of the keel, but what I can do is place equal amounts either side of the keel is that ok? Otherwise I am back to balancing it on the keel which again lifts the weight off of the bottom of the hull and not where it's really needed (the same as when the compartment was there).
Motors are coming out again today to get rid of the rest of this god awful compartment once and for all!
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Model Tug Man

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Re: Oh God I Need Help! - Images Added
« Reply #19 on: July 10, 2014, 05:36:23 »
Laying the ballast next to the keel should be fine. Weight in the boat acts like a lever against the center of boyancy. With the weight all the way down against the inside of the hull it will apply the maximum leverage to offset that of the superstructure. The only way you can do better is going outside the hull. Also, with the battery upright it is applying leverage against its contact point in the hull. Lay it down and you will be surprised at the difference. Keep us posted and good luck.
VGJQ

freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #20 on: July 10, 2014, 06:46:02 »
Thanks MTM,

I posted some images of my Preiser crew figures that arrived a few days ago,did you have a look?

Andy
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freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #21 on: July 10, 2014, 07:17:35 »
Update........Spent today removing the rest of the compartment with the exception of the other end piece as the two prop shafts come through the end of the old compartment and are supported at the ends by this wood. Should I remove this end piece as well?
I haven't got round to cutting a hole in the front bulkhead today but that is one of the next jobs on the agenda.

Does anyone on here cast their own ballast weights by any chance?

Also,if by adding all this ballast  it compromises the original waterline how do I go about re-doing it? The current one was already on there I just put the pin strlpe on to tidy it up a bit.                                                                                                                                                                                                                                                                                                                                                                                                 
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des

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Re: Oh God I Need Help! - Images Added
« Reply #22 on: July 10, 2014, 14:22:38 »
G'day Andy

I would first try to get the boat stable in the water with just the battery and upperworks in place.  Then worry about how she sits.

If she still sits bow high but otherwise still above her waterline, then firstly try to move the battery forward until she sits level.  If you can't move the battery, then you will need to add extra weight forward, but that will increase your overall weight, which may or may not ultimately be a good thing.  Alternatively, instead of adding weight forward, you could look at reducing weight aft.

Once you've got the model sitting level in the water, and stable side to side, with battery and upperworks installed, then you can look at where she floats relative to the waterline.  If she sits high, then more weight is needed.  No problem - there are numerous ways to add weight.

If she sits too low, then you need to reduce weight - preferably from the upperworks.  The higher up that you can remove any excess weight, the more stable the boat will be.  Yes, you can put in a smaller battery, but that removes weight from low down in the hull, thereby contributing to further instability.

Once you think you have it right in the bathtub, then you will need to CAREFULLY try it out on open water.  The difference is that the open water is more active, thereby causing the boat to rock 'n' roll.  Also, when you get to operate it, you introduce turns, which shift the centre of balance.  Both can highlight any need for further work on redistributing weight within the boat.

Good luck.

BTW,  have I mentioned yet that I think this is a good looking model.  Very well made - but apparently intended as a static model.  I can fully understand why you might be reluctant to carry out surgery on it.

Des.


freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #23 on: July 10, 2014, 14:40:44 »
Hi Des,

No, actually mate this old guy that used to build them was commissioned by someone to build her. The builder is now well in his 80's but I have spoken to him a couple of times and it was built to be used as an RC model. I think she is quite old but this was the way they were made donkeys years ago. I'm 51 now and I can remember as a child unearthing a part built steam tug in my dads old shed that he started to hand craft during his apprenticeship when he was 15-16 years old and this was made exactly the same. I think this is where my love of tugs originates from, never knew what happened to that old boat but I wish I still had it now.

Andy
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olscuzbut

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Re: Oh God I Need Help! - Images Added
« Reply #24 on: July 10, 2014, 16:03:04 »
Hi Des,
Don't get me wrong, I am not polking fun at your dilemma, but it so reminds me of a book I read a while back, by Farley Mowat called The Boat That Wouldn't Float.  Not that that is your problem, but he just seemed to continually run into snags getting his old boat to Montreal for the Expo.  Hope all your mods get you to a working conclusion.
Norm

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Re: Oh God I Need Help! - Images Added
« Reply #25 on: July 11, 2014, 03:35:48 »
A good read, that one.

Andy,

Do you have a photo of the boat sitting in the water that shows the entire waterline? Reason being that most tugs sit with their bow higher than their stern. The keel should not be parallel with the waterline. This is referred to as rise of floor. The boat will track better in the water with the stern down a bit and you will get a better bite on the water from the prop and the rudder.
VGJQ

freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #26 on: July 11, 2014, 06:30:34 »
Hi MTM,

Are the images any good at the beginning of this thread? It's quite difficult to get a good image due to the height of the bath sides.
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freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #27 on: July 12, 2014, 01:06:21 »
Right, had a day off from chopping my tug up yesterday, I went searching for lead supplies for the ballasting. That's not cheap either but I ordered a load of 2Lb ingots to start off with. I did consider the local church roof for the lead but thought better of it as I'm not really keen on heights  :)

Will be cutting through the front bulkhead today and then I must search through the garage for my lead melter it's so much cheaper to buy and re-melt sea fishing weights than it is to buy scrap lead!   


« Last Edit: July 12, 2014, 10:02:39 by freightliner009 »
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freightliner009

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Re: Oh God I Need Help! - Images Added
« Reply #28 on: July 12, 2014, 08:35:03 »
Here are the latest batch of images after the removal of the electronics compartment.........

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A close up after the chop through the end bulkhead........

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This was the rough position of the battery as it was, standing upright and of course higher up initially in the 'old' compartment.......

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This is the new battery position, lying on its side and now quite a bit further forward too, this surely must make a difference?.......

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And finally the opposite end of the old compartment, I decided to leave this in place at the moment as it supports the prop shafts but if you thinkk should go then please let me know?.......

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All continued thoughts are welcome.

Andy.             
« Last Edit: July 12, 2014, 12:01:47 by freightliner009 »
Proud  father of a new Hobby Engine 1/35 scale Southampton tug and 1/24 scale hand crafted Zeeland tug

CORONA

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Re: Oh God I Need Help! - Images Added
« Reply #29 on: July 12, 2014, 09:29:46 »
Is it just me or are the photos not showing up ?
Indicates all five were moved or deleted,  at leaston my computer........

Laurn