Model Boat Mayhem

Mess Deck: General Section => Model Boating => Topic started by: U-33 on April 20, 2017, 03:16:19 pm

Title: How to do this... ( reshape the bow section )
Post by: U-33 on April 20, 2017, 03:16:19 pm
Right chaps...if all goes well and I can get a destroyer hull, I'll need to reshape the bow section. Any ideas as to how to go from the left hand image to the right hand image?
Title: Re: How to do this...
Post by: dougal99 on April 20, 2017, 04:06:32 pm
An isometric drawing would be a good start. As  it is, it is difficult to see what you are trying to achieve.
Title: Re: How to do this...
Post by: U-33 on April 20, 2017, 04:27:13 pm
Eh? 
Title: Re: How to do this...
Post by: davidm1945 on April 20, 2017, 05:21:21 pm
I've seen lots of ships with the left-hand bow shape but what is the right-hand one? Can you elucidate?  %)

Dave.
Title: Re: How to do this...
Post by: tattooed on April 20, 2017, 07:11:30 pm
are you building the uss zumwalt rich
Title: Re: How to do this...
Post by: U-33 on April 20, 2017, 08:18:42 pm
Not Zumwalt mate...a sort of semi scale Sea Wraith.
Title: Re: How to do this...
Post by: dougal99 on April 20, 2017, 10:01:31 pm
Is this the type of thing? if so a standard hull will need some major plastic surgery. The bow will probably have to be removed at around the point of maximum beam and the a new bow created in the desired shape. I recommend a test rig from cardboard and balsa. Good luck.
Title: Re: How to do this...
Post by: U-33 on April 20, 2017, 10:16:47 pm
That's more or less it...it'll be fun and games doing it. I sense boxes of filler....
Title: Re: How to do this...
Post by: ballastanksian on April 20, 2017, 10:27:16 pm
It is a shame the card kit of Sea wraith seems to be unavailable as this would give you much of the plate shapes etc that could just be enlarged.

What are you going to do with the destroyer bow if you do go down the modifcation route?
Title: Re: How to do this...
Post by: malcolmfrary on April 21, 2017, 08:14:50 am
Eh?
Isometric drawing - take the front, side and top views and combine them to get a 3D view on 2D paper with the right dimensions but lacking perspective.
Title: Re: How to do this...
Post by: tigertiger on April 21, 2017, 08:17:11 am
I think you mean orthographic projection.
Pic 1


Isometric is pic 2.



Title: Re: How to do this...
Post by: U-33 on April 21, 2017, 08:40:04 am
I knew I shouldn't have posted this.. :embarrassed:  farr too technical for an old fart like me.


Right, I don't want to go too radical with the bow shape, the pic that Dougal put up is about right...maybe a bit too much, but along those lines.
I was thinking of using a block of balsa epoxied into the bows (after cutting the existing piece out) and then sanding it to shape...a coat of resin over it to protect it should strengthen it sufficently.


A superstructure built up from thin styrene sheet, in a series of odd shaped boxes to give it that 'stealth' look, with the running gear consisting of two motors/shafts/rudders and a water pump based bow thruster. And that is basically it...I did have a go at one a few years back, based on a styrene yacht hull, but I built the superstructure far too heavy, and the finished product kept falling over, so it ended up being filed under B1N.
Title: Re: How to do this...
Post by: tigertiger on April 21, 2017, 09:19:29 am

If we can establish the basic shape you want, that will give us good start point.
OK, looking at your original pics, it looks like your bow goes deeper into the water as you go forward. And the frames would be, in part, like upside-down triangles. Like in the Att pic. Is that correct?


If it is like the pic, it gives an idea of the frame profiles you would need. You could then use planks and flat pieces of balsa as needed, and carve a block of balsa for the 'nose'.

More pics here https://www.google.com/imgres?imgurl=http%3A%2F%2Fblufiles.storage.msn.com%2Fy1plUZMLq02hf3N0j7XyssIQOKpnFw9fO-v6A8cOqW2fHUYO447ii3LH4lMhDY_yCwWwiH3Wqu0xtUE2UciEltHhw%3FPARTNER%3DWRITER&imgrefurl=https%3A%2F%2Fdtashji.wordpress.com%2F2008%2F01%2F01%2Fnaval-forces-changing-course-from-blue-water-to-the-littoral%2F&docid=5rR95xkMnlEdDM&tbnid=9rcDz5-Rpa_ORM%3A&vet=10ahUKEwiNldOBj7XTAhUD3GMKHSZ1DNUQMwhMKB8wHw..i&w=599&h=449&bih=490&biw=1093&q=wave%20cutter%20hull%20shape&ved=0ahUKEwiNldOBj7XTAhUD3GMKHSZ1DNUQMwhMKB8wHw&iact=mrc&uact=8
Title: Re: How to do this...
Post by: dougal99 on April 21, 2017, 09:20:18 am
Block balsa is one way to go but where (how far back) would you put your bow thruster?
Title: Re: How to do this...
Post by: U-33 on April 21, 2017, 09:38:45 am
TT...you are spot on there, sir. That's the sort of thing I'm after creating...


Dougal...you have discovered a fatal flaw in my idea...maybe the bow thruster would end up becoming a centre thruster.  :embarrassed:
Title: Re: How to do this...
Post by: tigertiger on April 21, 2017, 09:44:25 am
These might work. Bow thruster would need a bit of fancy plumbing instead of the usual straight pipe.
Title: Re: How to do this...
Post by: U-33 on April 21, 2017, 10:02:41 am
Now we're getting somewhere...the bow thruster will be nothing more than a screenwash pump, sucking water in one way and blowing it out of the other. Dead simple, easy to plumb in using silicone tubing, and above all...it works.


Thanks TT...you've hit the spot there.
Title: Re: How to do this...
Post by: tigertiger on April 21, 2017, 12:38:43 pm
Glad I could be of help  :-))


The only other thing I would add is 'L' pieces on the ends of the silicon pipe to help the water out at useful angles, more easily..
Title: Re: How to do this...
Post by: U-33 on April 21, 2017, 12:43:12 pm
Top man, TT...  :kiss:
Title: Re: How to do this...
Post by: surfs up on April 21, 2017, 12:54:03 pm
Here are some photos of my HMS Vectra, the front is a chunk of balsa the rest is 1/16 ply.
Title: Re: How to do this...
Post by: U-33 on April 21, 2017, 01:10:02 pm
Now that is as near as dammit what I want to do Surf...what scale/size is that?


I've sent you a pm, by the way..
Title: Re: How to do this...
Post by: surfs up on April 21, 2017, 01:48:23 pm
Rich
pm returned


Surf
Title: Re: How to do this...
Post by: Big Ada on April 21, 2017, 06:03:40 pm
Wont that turn in to a Sub if it hits a Wave head on ?. %)

Len.
Title: Re: How to do this...
Post by: U-33 on April 21, 2017, 08:01:53 pm
Umm...it shouldn't do.
Title: Re: How to do this...
Post by: U-33 on April 21, 2017, 08:30:08 pm
I'm sort of thinking that the easiest way to achieve this is to use one of Glynn Guest's destroyer plans, and building the new bow shape into/onto it. That would save  hacking a perfectly good fibreglass hull to pieces, I think.
Title: Re: How to do this...
Post by: steamboatmodel on April 21, 2017, 10:17:50 pm

I think it would be a very wet decked boat.
What is the idea behind it?
Not a bow ram I hope!
Gerald.
Title: Re: How to do this...
Post by: bikerdude999 on April 23, 2017, 11:22:23 pm
There are 2 plans available, HMS Vectra at approx 1.4m long I think, with little detail to go on, there is also HMS Spectre, which I think is essentially the same but around half the size, and may have more detail to it. I've already got the Vectra plans but might get the spectre plans too sometime and hope they have more detail.
Title: Re: How to do this...
Post by: tigertiger on April 24, 2017, 01:27:35 am
It might be better to work from plans, because the hydro-dynamics are completely different to what most of us have seen before. One person hinted at submarining, which could be a case if you get the balance between down forces and up forces wrong. Wave piercing is, I guess, a balanced momentary submarining. You could probably do this through trial and error, to get a model that sails well, but the cost of redoing several times is probably more than buying plans.


The other thing I noticed, on the pic I posted earlier, is that the transition is amidships, it is much more than just the bow.


My 2 cents
Title: Re: How to do this...
Post by: U-33 on April 24, 2017, 10:41:04 am
Thank you, gentlemen....your comments and advice are most gratefully received. I've just managed to delete my whole folder of 'stuff' related to these craft from my laptop, so as you may guess, I'm not very happy about that... >>:-(


Thank you all again...
Title: Re: How to do this...
Post by: dougal99 on April 24, 2017, 10:55:28 am
Are you using Windows? If so right click on the folder that uses to contain your data and click restore previous version. Otherwise google recovering deleted files.
Best of luck
Title: Re: How to do this... ( reshape the bow section )
Post by: Tug-Kenny RIP on April 24, 2017, 11:07:47 am
I would say to recover the data.

It's your interest and a very interesting subject.  You certainly have roused the member's attentions and have had quite a few views on the subject..

Keep going,  you may be onto something.   :-))

ken

Title: Re: How to do this... ( reshape the bow section )
Post by: ballastanksian on April 24, 2017, 02:52:11 pm
The Bow shape is similar to that for X Bow vessels in that the bow is designed to break up waves. It was found eons ago that the ram bows of Pre dreadnoughts etc had a similar effect and this has been brought back for merchant ships as Bulbs and as you see here as a fully developed bow.

It probably has the same strength as any modern ship's bow and so would crumple rather if used as a ram!!!!

Title: Re: How to do this... ( reshape the bow section )
Post by: tigertiger on April 25, 2017, 02:40:49 am
For cargo vessels, the need to maximize hull capacity may be why a bulb has been used. The stiletto would make no sense, other than fuel efficiency and more stable ride.
For military it may be that speed and stealth technology (reducing radar profile) may explain the lines that are chosen. The only downside is reduced deck/weapons carrying/operational area.
I also read that the X-Bow is starting to be used on cargo and military vessels. I guess it takes time for new ideas to be adopted, and the X-Bow is a fairly new (2006) technology.
Title: Re: How to do this... ( reshape the bow section )
Post by: ballastanksian on April 25, 2017, 08:10:14 pm
Makes perfect sense TT.