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[TailUK]

I'm putting this here because it about a warship and it a possible build for me soon.
 
I'm thinking of creating the master for a GRP hull of a Victorian Torpedo Boat to 1:50 scale (about 800 mm long)  The boat has wierd cross sections but thats not really a problem.  Without having to engineer a lift out section in the curved upper section there is only a narrow walkway down the length of the boat (marked in red on the pic) This should be wide enough for acces to the receiver, servo and battery but if major work was required it would be too constricted.
 
My question is this if I built it so that the hull could split along the line of the strake (Marked blue in the picture)  Do the group think that it's
A)  Too close to the waterline
B)  Too big a join to be sealed effectively  (It would run 95% the length of the ship)
 
       I'd appreciate any insights on the problem before I start slopping resin around, also any ideas about the form a join like that would take would be welcome.
 

[tonyH]

It actually works quite well splitting the hull, even at the waterline, because you dont have to disconnect any rigging etc. The only problem I've had is the rudder linkage at times.
I'll take a couple of pics of the cruiser I'm building at the moment to illustrate my method anyway and post them later.
 
Tony

[Perkasaman2]

This is a very interesting project. Could you not bond the forward third of the top hull section since its going to be empty and seal off the bow section. Ingress of water will come from the bow waves, however, if you fit chine rails similar to the later CMB then these should deflect the water quite well when the hull is at speed. Just a few quick thoughts. 

[tonyH]

Herewith the pics (I hope!)  The split follows the top of the wooden cladding but on a previous boat it was on the waterline. The internal coaming is about 2.5cm high (the model is about 1m).
 
The only problem is getting the rudder action to the right place.
 
The top and bottom are held together with the two screws where one is the capstan and the other is a ventilator, both screwed into captive nuts in the lower half.
 
You might also consider the waterline for the split since it is, or should be probably, a straight line.
 
Good Luck  

[TailUK]

This is a very interesting project. Could you not bond the forward third of the top hull section since its going to be empty and seal off the bow section. Ingress of water will come from the bow waves, however, if you fit chine rails similar to the later CMB then these should deflect the water quite well when the hull is at speed. Just a few quick thoughts. 

Thanks for your thoughts.  I didn't want to seperate the top section into pieces if I could avoid it but I take the point about the bow section.
I am thinking about adding bilge keels as it looks as if the boat would roll on wet grass given a chance.

[TailUK]

Herewith the pics (I hope!)  The split follows the top of the wooden cladding but on a previous boat it was on the waterline. The internal coaming is about 2.5cm high (the model is about 1m).
 
The only problem is getting the rudder action to the right place.
 
The top and bottom are held together with the two screws where one is the capstan and the other is a ventilator, both screwed into captive nuts in the lower half.
 
You might also consider the waterline for the split since it is, or should be probably, a straight line.
 
Good Luck

Looks good, if I split the hull along the strake line in a similar manner it would solve the problem    Do you put sealant or a gasket between the upper and lower?

[Perkasaman2]

 Hi Tail, could you post a pic of the original to visualize the hull. It could be tough to predict where the waterline will be relative to the hull joint. I am assuming that the boat has a 'slender' cigar shaped hull.
I can faintly recall a mention/picture of this boat in a book concerned with the history of destroyers I read quite some years ago.   

[TailUK]

Here's a CGI image of t'interweb.  You can see the waterline and the strake line where I imagine the hull could be split.

[tonyH]

Hi Tail,
 
If you make the horizontal pseudo-decks as a pair and fit the lower one first with its pseudo-bulwark, you can then screw the upper pseudo-deck to the lower one and then add its bulwark. It's worth putting temporary bits of thin card as spacers between the two sets of bulwarks to give a tad of leeway for paint or varnish. Once it's all set, you can unscrew the two decks and they should match pretty well. The only sealant I used was a smear of vaseline.
 
Don't forget, you can take the inner bulwarks almost up to the deck so even if you have the join below the waterline, the innards should remain dry.
 
 
Good Luck  

[Circlip]

If you want a belt and braces seal, you could use small diameter thin walled rubber tubing and make it into an "O"-ring to go round the split line. Same effect as an O-ring, but a lot easier to compress. Same stuff that bike valve rubbers were from.
 
  Regards  Ian

[RAAArtyGunner]

 
In reply #7 the prop is aft of the rudder??
 
So in effect it is pushing the steerage???
 
Was that design/propulsion unsuccessful hence reverting to the conventional of rudder aft of the prop.

PS. Further thought, is this a twin prop vessel, as the rudder or prop would be offset, from the centreline, so that the rudder throw is not 'fouled'.

[tonyH]

Aaaaaargh - the pointy thing awakens from the deep
 
Don't worry RAAArty, we're not mad but you need to read the last posts on  http://www.modelboatmayhem.co.uk/forum/index.php/topic,17389.msg239309.html#msg239309
Then forget the whole thing!
 
Tony

[RAAArtyGunner]

 
Done, 
 
We awaken as the sun is now shinning for the first time in several days

[BrianB6]

Ah! So that's where it went. 

[RAAArtyGunner]

Not too worry its gone again, probably back south to you the rain is back for another week  and  maybe a cyclone as well

[Perkasaman2]

I am impressed by TonyH's ingenious solution and Circlip's tubing idea.
The picture of the boat is really helpful in visualizing the hull ......... Is there a small rudder under the bow to assist steering?
It's strange seeing the bow shape and rudder/prop arrangement on these early ships. It's surprising that the early designers did'nt realize the limitations of these features.

[TailUK]

In reply #7 the prop is aft of the rudder??
 
So in effect it is pushing the steerage???
 
Was that design/propulsion unsuccessful hence reverting to the conventional of rudder aft of the prop.

PS. Further thought, is this a twin prop vessel, as the rudder or prop would be offset, from the centreline, so that the rudder throw is not 'fouled'.

I don't have any information on how effective the set up was.  The single screw was indeed behind the rudder, in fact the rudder pivot was attached to the prop tube, which itself was part of the keel.  It will be interesting to see how the model handles.
The small rudder at the bow was common in this era HMS Polythemus had a similar set up.  I, personally, think that the small rudder was an "attack" rudder  to allow fine tweaking of the course during an torpedo run.

[Circlip]

Just had another thought on the rubber tube saga. If you go to a plastic window/door manufacturer/supplier and enquire about "P" gasket - - - the other gasket sections they use may also be of interest.
 
   Regards  Ian.

[tonyH]

Hi Tail,
 
From experience with Arquebuse (See the later posts in the link in reply 12) a narrow hull with the prop(s) aft of the rudder means she will steer unbelievably badly.
This is from experimental results with a 1 metre model.
 

[tghsmith]

actually have been looking at 2 U.S.N. torpedo boats of the same vintage,1/48th scale. my thinking having the entire deck removable at the strake(rub rail) with flat deck and combing on the hull section is the way to proceed, thin sheet unicelluar foam should be fine for gaskets.. as for the rudder looks like there is a small forward steering rudder(would be interesting if it was part of the original design or an after thought) not many torpedo boats in this frame turned well..

[PICKETBOAT]

Hi Tail
Your proposed model should sail without the addition of a non-scale keel or external weight, but you will have to be very careful that you keep much of the weight low down in the hull.  Every gram will count so don’t populate the deck with lots of white metal fittings.  Build all deck structures very light.
 
I built TB75 (a 125ft first class torpedo boat by Yarrow 1887) at 1/48^th scale which also has a glass fibre hull. It sails very well. If it helps in your design, I used two flat AA receiver packs flat on the hull floor wired to give 4.8V. This provided the vast majority of the ballast and propelled the model at a scale 19 knots.
 
I cut an oblong deck aperture to gain access to the internals. This deck hatch sits on a register (lip) made of plastic card and is held down with two disguised screws. The secret is to use a bead of (brown) silicon to along the register to create a watertight seal. Apply a release agent to the underside of the deck hatch edge so that it is not stuck down permanently! The model has sailed in some choppy conditions and is 100% watertight.
 
The bow rudder on these vessels was of course retractable and seems to have been deployed when manoeuvring in confined conditions or going astern. It would reduce speed so they might not have used it at “attack speed”. I’m currently building a Russian vessel and plan to fit a functioning bow rudder to see how effective it actually was.   
 
Keep us all posted with the build.

[TailUK]

Hi Tail
Your proposed model should sail without the addition of a non-scale keel or external weight, but you will have to be very careful that you keep much of the weight low down in the hull.  Every gram will count so don’t populate the deck with lots of white metal fittings.  Build all deck structures very light.
 
I built TB75 (a 125ft first class torpedo boat by Yarrow 1887) at 1/48^th scale which also has a glass fibre hull. It sails very well. If it helps in your design, I used two flat AA receiver packs flat on the hull floor wired to give 4.8V. This provided the vast majority of the ballast and propelled the model at a scale 19 knots.
 
I cut an oblong deck aperture to gain access to the internals. This deck hatch sits on a register (lip) made of plastic card and is held down with two disguised screws. The secret is to use a bead of (brown) silicon to along the register to create a watertight seal. Apply a release agent to the underside of the deck hatch edge so that it is not stuck down permanently! The model has sailed in some choppy conditions and is 100% watertight.
 
The bow rudder on these vessels was of course retractable and seems to have been deployed when manoeuvring in confined conditions or going astern. It would reduce speed so they might not have used it at “attack speed”. I’m currently building a Russian vessel and plan to fit a functioning bow rudder to see how effective it actually was.   
 
Keep us all posted with the build.

Super looking model!  Pressure of work has held up the "Adler" but I hope to start the hull plug soon.