Naval Tug ? Mk2

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ivorthediver
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Naval Tug ? Mk2

Unread post by ivorthediver »

Those of you who viewed the WNSF might remember that the most detailed of builds shown on there which ran through all her mods and indeed misadventures was the post on Tugs .......No don't panic I won't subject you to a rerun of that :o

You may also have noted whilst viewing this thread that I mentioned I was having problems transferring some photos from my iMac to this system .....well I seem to have found the answer ......so as there are no other "As built studies on here yet I will show you the work that took 18 months via a short collection of sage build photos on my current model which is a scale version of a Damon type 2810 ASD Tug .

Now before you all start complaining , above the waterline " is as " whilst beneath by necessity is not fully accurate as the ASD refers to "Azimuth Stern Drive" where due to cost and procurement, this model has steerable twin Kort drives , other than that there are no known differences I'm aware of .[ gulp]


So to start the ball rolling a tad of background , the previous tug I built suffered from from my stupidity in thinking a branded copy of my radio control system receiver bought on the internet was the genuine article at basement prices ......WRONG .....and the cost to me was very dear as having spent just shy of 1K building , kitting out , and constructing , finishing the model the Radio kit was sent in for servicing by the manufacturers , the receiver was not,.. as thought to be sound [ for sound read new ] and once "Paired" up with the transmitter thought to be ok .....only to have it go into spasm, turn turtle and sink in deep ink black water never to be seen again :evil: .

It transpired that I was in fact covered by insurance so set about the whole thing again but decided to build the Damon 2810 instead , with me so far :)

Ok the following shots show the lining up of the prop-shafts, determining the centre line of the hull, and installing the motors and prop supports .
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ivorthediver
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Re: Naval Tug ? Mk2

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You may have noticed the last picture of the upturned hull shows a black line on the side which is where I fitted a pair of bilge keels to offer stability in tight turns , and an extra hole beneath the prop , which is where the Kort Nozzle is fitted which encases the prop in a shroud thereby funnelling the prop wash in a concentrated line which intern is directed on the same basis as a traditional rudder would.... X.. 2 .by the alteration of the nozzles in sync ......pay attention there ....there will be questions later.

Moving forward from this the kort nozzles need to be fitted and aligned in parallel
to facilitate manoeuvring in both directions and connected to each other via the rudder servo system .

The other picture shows the partial fitting of the deck forward [ which is elevated] and aft which was fed into the recess in the hull moulding [.which was developed for another model but adapted to suit my requirements ] which is a fibreglass mould in orange colour and suited in general size to my model but needed a lot of work to adapt]

Yes yo usan buy kits ready to make but NOT my bag , as I prefer to design and build as I go along and avoid hull structures where possible [ I know my limitations :oops: ]

So far so good .
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jbryce1437
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Re: Naval Tug ? Mk2

Unread post by jbryce1437 »

A brilliant piece of work Ivor and a credit to your skill and ingenuity, as was the old tug.

Jim
HMS Raleigh 1963 , HMS Collingwood 1963 & 67 , HMS Ark Royal 1964-7, HMS Undaunted 1968-71, HMS Victory (Fleet Maintenance Group) 1971-72, HMS Exmouth 1972-74
JEM, EM, OEM, LOEM, POOEL
Then 28 years in the Fire Brigade
Retired since 2002
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ivorthediver
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Re: Naval Tug ? Mk2

Unread post by ivorthediver »

Flattery always welcome Jim it helps me overcome my own inadequacies

Thank you very much ., coming from you a compliment indeed , but we all have our strengths and weaknesses , I'm just trying to balance the good bits agin the bad .
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ivorthediver
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Re: Naval Tug ? Mk2

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Having got the deck profile inserted and dried to restrict flexing of the hull whilst working on it the next step whilst access permitted was to cut a hole in the bottom of the bow to insert a Bow thruster which is an optional extra to basic but knowing her intended use was for recovery of other vessels ,manoeuvrability is essential .

So I chose the largest that would fit given the scale [ 1/25] I purchased a Bow thruster and fitted it as close to the keel line as was practical along with a brass wire grill to deter the entry of crud which might foul the impeller duct contained therein

This then opens up additional problems in that the popular ones on sale are supplied only with 7.5v motors .....not what the rest of the model is supplied on which was 12v,

To overcome this issue I had to purchase a separate electronic speed controller to operate it and due to its close proximity to the bow requires careful planning and siting .
This is due to one of the most important build / cable management criteria .

You will notice that the rear of the hull visible was fitted with a bulk head big enough to accommodate the two batteries planned to be fitted which were to be used as ballast as well as power supply .with the supply cables running beneath the deck line to the mains distribution board in front of the batteries on a vertical stand

Before installing components in Radio Control models you have to plan your cable runs to ensure that power and and control servo leads are on opposite sides of the hull to minimise interference whilst in operation .

With some fore thought this can be done in most cases , and before fitting any functional item you must fit in the most suitable position without attracting signal lose from long servo leads ......a compromise

So having solved that issue you then fix items as far away from both accidental wetting and interference to gain the maximum benefit

In addition and from experience gained on the previous tug I angled the exit ports of the bow thruster down to gain extra purchase when in use , which worked very well .

Another thing I always do is to fit a deck inside the bottom of the model which apart from stiffening the hull also gives a level platform to place your accessories on and on which to fit items via velcro to keep them in place , and the deck offers some water resistance should you be unfortunate enough to get penetration through the bottom of the hull , in this instance mine are held in place by silicone sealant prior to painting .

You will also see the top of the inspection panel giving access to the direction servo which will control the Kort thrusters , and the sealed section between the battery section and the servo local was filled with foam to act as a floatation chamber and then sealed with silicone again .
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ivorthediver
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Re: Naval Tug ? Mk2

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I'm sure you will have noticed that the hull was designed as an Anchor moving vessel for use in the oil / Gas fields by the large gap in the stern bulwark used to drag the sea anchors on board / set down when re- sitting the platforms in there required location

This was overcome by lining all the inside of the bulwarks internally [which also hides the grainy glass fibre strands] with Styrene sheet and body filler externally .

Then the vertical support rakes were fitted after building each one and glueing into position after the hawser rings were fitted, and then the fiddly bit of marking out the topping cap and sanding to shape
Remember this is a Working Model ....not intended to be admired in a glass case and dusted

The towing points and Panama style guides and were bolted through the decks [ 8mm external ply once all edges were sealed ] and are very secure and made of white metal reinforced with steel innards which on this occasion I bought, as plastic fabricated ones are easy enough but not strong enough to tow with , again found out by trial and error , and as said initially she certainly WOULD be pulling loads of varying weights .



You can easily fabricate them using the cogs out of broken servo's and designing the type you require to fit add a short section of chain over the drums and your there :idea:

Then the rubber booting was glued into place and rubber racking strips for the daring other modellers who might try ramming you :evil:

In more recent pictures you will see that these are overlaid at set intervals with yellow tie wraps to mimic the current fitting system Damon use to retain the pressure and absorbency on contact with the new carrier and all painted Admiralty grey to minimise marking the hull's with black scuffs :roll:

All these things need to be thought through before you start and built in sequence to avoid expensive reworking of the hull

A case in hand to illustrate this point :-

You can see the access point in the rear right hand corner of the aft deck used to gain access to the direction servo system .

Later on once completed this had to be all cut open , enlarged and all the direction linkages , servo mounts , and Kort shafts had to be taken out and replaced with new ones as the original resin ones purchased went oval and the very expensive props were beating hell out of them .......so new cast aluminium ones were custom made and fitted along with cast bronze 5 Blade kort prop's ......a very annoying and expensive experience not to be repeated .....so on reconstruction the access panel now runs the full width of the stern deck to allow for any future alignment problems .......she may be only a model.... but I often wonder if it would have been better to buy a proper boat ......hang on ......the wife just fainted ......so I might be in A&E for a while recovering.... when she regains consciousness :shock:
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ivorthediver
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Re: Naval Tug ? Mk2

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To finish off the detail on the Korts Drive installation , which I'm trying not to make a saga of , One thing that did become evident during the final stages of the old Korts fittings was that whilst every care was taken during launch and recovery.. it might have been a case of the bottom of the nozzles dragging on the ground when it came in..... and as I said I wasn't aware of any occasions when it may have happened but the possibility exists .

To ensure this din't occur on the replacements I asked the supplier to fit a pin on the bottom of each one so that I could deter or avoid any future damage issues .

Upon receipt of them I made up two cups to fit over these pins and silver soldered a length of 5mm brass rod at right angle to them and bent these rods to the same profile of the underside of the hull and placed them in a small section of brass tube to act as a sleeve which was wrapped and soldered in a piece of brass sheet and bent to fit behind the "P" brackets supporting the prop shaft ends ......
yes bit confusing but basically a skeg fitted in a piston to allow it to slide as the nozzle rotates which supports the bottom of each nozzle and protects it from being pushed should it ground in the shallows :idea:

It appears to work well viewed out of the water whilst in action and gives me piece of mind , and I must admit to like a bit of silver soldering .

The attached sketch shows the area of work but NOT what I have just described
but i'm sure you can work it out for yourself .
I have tried to retrieve the sketch which was sent to the builder of the NEW KORTS Ports.... indicating the Dims required but was unable so basically follow the bottom contour and imagine the keg support which runs lower but parallel to the prop shaft :|
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ivorthediver
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Re: Naval Tug ? Mk2

Unread post by ivorthediver »

Ok I've taken pity on you and copied / added to the original sketch to try and simplify explanation re Kort mod's

Again its A.. about face but should make it a little clearer I hope , if you look at the left hand side which is the keel of the tug and the profiled rod fitting into the sleeve which slides but adds support to the bottom of the Kort 's :D

Right time to move on now . :)
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ivorthediver
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Re: Naval Tug ? Mk2

Unread post by ivorthediver »

As a point of reference here is a shot of a pair of Kort driven Damon Tugs being refitted.

You will see what a Kort Drive is but should point out the differing types in general use
currently :- ASD....... Azimuth stern drive generally utilising engines like Caterpillar
3516c Engines [5000 bhp@1600rpm]
2xRolls Royce us205 Thrusters
prop's 2400mm from which they can
manage 57 ton bollard pull ahead
" 53.5 " " astern
Max speed12.9 knots

ART 80-32. Hybrid systems:-

Generally utilising 3 Caterpillar 3512c eng
[7095 Bhp @ 1800rpm]
3x Schottel SRP3000FP Trusters
3x Schottel fixed pitch propellers
fitted in 3x 2300mm SDN55 nozzles
from these three drives they can
manage a 85.3 ton bollard pull ahead
" " 86.0 ton " " astern

So quite a different animal both of which are both very comfortable for crews working long hours and fitted with all mod cons to a very high standard being Air conditioned and centrally heated throughout

These are just two of the range for a comparison .
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ivorthediver
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Re: Naval Tug ? Mk2

Unread post by ivorthediver »

Right lads .....to continue the build programs cycle .

The next step was to build the superstructure .

The bottom picture shows the front beneath the deck where the cable runs , Distribution panels , battery storage area , and layout .

The next picture up shows the superstructure base which is built of ply and plastic and is taking the general form of the main accommodation area / engine room / service block , formed on a set of ribs for strength and over plated and glues and then the apertures , details are added piecemeal .

The first shows the shape and style of the bridge / railings and basic form and proportions .

To reach this point has taken approx 6 weeks of scaling , designing , constructing , acquiring artefacts and base cost priming .

You will see that the bulwark handrail is now fitted and the vertical support of the bulwark added and painted and the paint scheme decided
this adds a further month of work , baring in mind I'm semi-retired and work as and when the inspiration dictates and the pocket allows . ;)
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