how do I mark off a waterline

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how do I mark off a waterline

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3 August 2012 at 00:51 #2163
murphy 1570
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@murphy1570
I
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3 August 2012 at 00:51 #35585
murphy 1570
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@murphy1570
As a relative beginner to building model boats I have almost completed building a WWII MTB, and I am at the painting stage, I have sprayed the hul grey to the best of my abilities and I want to spray the hull below the waterline with red oxide using Halfords spray cans, but I am having great difficulty in trying to mark of the waterline accurately as shown on the plan, I have tried it both right way up and also upside down ie inverted, and am about at the end of my tether (cracking up !!) if truth be known, I have been working on this model for about 5 months it is of ply and balsa construction, I am at the stage where the wife is threatening toevict me from the kitchen table where most of the build was done except for the spraying, which was done on the odd sunny day we have had this summer!!!!!

Any help and advice would be welcome, thanks in advance for any replies.

John.
3 August 2012 at 03:04 #35588
Eric Moffat 1
Participant
@ericmoffat1
G'day John,

I usually cut a strip of paper about 12 – 24mm wide, and using paper glue stick it on the hull around where the water line would be, place the hull in the water and mark where the water line shows. wash off the paper and paint away!

Regards

Eric
3 August 2012 at 08:04 #35589
Gareth Jones
Participant
@garethjones79649
Hi John,

I usually mount the hull on its stand on the top of my bench (or kitchen table in your case) so that the waterline will be level. Depending on your stand, you may have to pack up one end or the other using scrap timber so that the angle of the hull matches what is shown on your plans and gives a horizontal waterline parallel to your table top.

I then make up a pencil holder using a block of wood, square and a few clamps as shown in the photo below.

The pencil usually has to be angled up slightly to give the best position to mark the hull where it is curved. A bit of trial and error is usually necessary. When you are satisfied the tip of the pencil is at the right height, just slide the whole assembly along the bench and mark the line along both sides of the hull
3 August 2012 at 09:26 #35591
Colin Bishop
Moderator
@colinbishop34627
I use the same method as Gareth but you do have to be a bit careful with sections of the hull which curve in sharply towards the bottom of the boat. Counter sterns for example.

Colin
3 August 2012 at 10:48 #35592
Paul Freshney
Participant
@paulfreshney24971
I do as Gareth and Colin do, but always mark a couple of milimetres higher (or lower) than required. Why? Well I mask the bit I don't want painted parallel to this marked line (the couple of milimetres difference), so that the paint being applied then covers the pencil line because I have seen a number of models where the pencil line still shows along the edge of a painted section. Use a soft pencil and Tamiya masking tape is excellent, leaving no residue or lifting paint from underneath it. For big sections of the hull, I now use kitchen foil. Easy to 'crush' to shape, impervious to paint and easy to stick to the Tamiya tape with ordinary cheap brown sticky 'car' masking 25mm wide tape.

Paul Freshney
3 August 2012 at 10:51 #35593
Kimosubby Shipyards
Participant
@kimosubbyshipyards
Hi John and all,

yes, a very similar method used by myself, I have a hole drilled through the upright timber Gareth shows and stuff the pencil in that.

You do need space all about the vessel so that both sides can be done in one sitting, of course, having checked the boat "levels" before during and after the scribing.

I have one other check – I use a red laser beam just to confirm the pencil line hasn't drifted, as Colin says, where the hull curves inwards, usually at the stern.

As a point of interest, the laser I have also has the crossed beams, one at right angles to the other, and this is also very helpfull when getting deck furniture and fittings (even masts) upright when against the waterline as apposed to the deck in the vacinity. Mast rake can be set using this method and a digital spirit level!

Happy building, mind that table – your next meal comes from that area, Kimosubby.
3 August 2012 at 11:54 #35594
Colin Bishop
Moderator
@colinbishop34627
The laser line idea is ingenious, I hadn't thought of that. Do you use any particular type Kim?

Colin
3 August 2012 at 17:54 #35597
Paul T
Participant
@pault84577
Its a bit over the top but I use a rotary laser level like the one pictured, its a piece of kit that I used in my working days.

Like most people I have a shed full of tools and kit that now gets used less than Santas sled.

Edited By Paul T (fat controller) on 03/08/2012 17:58:44
3 August 2012 at 18:41 #35601
Kimosubby Shipyards
Participant
@kimosubbyshipyards
Colin,

I looked and I have two types, one from Black and Decker, single line, tripod mounting with spirit bubbles for all dimensions – solid build and good for the horizontal water line checking. I had an idea to use it for wall papering etc but still use the tried and tested plumbob.

The othe came from Maplins – type LS 305 – and has beams at right angles. Unit has spirit bubbles as well and can be used on any flat platform (I bolt it to a tripod as heoght adjustment is much easier.)

Kimosubby.
3 August 2012 at 19:03 #35602
Bob Abell 2
Participant
@bobabell2
Using lateral thinking……..

Fill the bath with red paint……..and float yer boat!

Remove and allow to dry

Blimey!….These pills are a bit strong!

Bob
3 August 2012 at 22:36 #35611
Colin Bishop
Moderator
@colinbishop34627
No good Bob, how do you deal with the boot topping?

Colin
3 August 2012 at 23:04 #35612
Bob Abell 2
Participant
@bobabell2
Boot topping?

Sorry, can't find my Enigma machine at the mo!

Boot topping?………eh?

Geez!……These pills are really strong!

Bobl
3 August 2012 at 23:18 #35614
Colin Bishop
Moderator
@colinbishop34627
Don't worry Bob, just fill your bath with red paint and then add a couple of litres of indian ink on top – job done!

Colin
4 August 2012 at 06:07 #35617
Paul T
Participant
@pault84577
Hello Bob

You know the meds are strong when you find yourself counting your fingers before you start cutting.

Paul
6 August 2012 at 01:13 #35653
murphy 1570
Participant
@murphy1570
Hello folks

May I take this opportunity to thank all who responded to my ouestion re marking a waterline, lots of good advice including the funny ones, but I think I will need to take special care of the kitchen table as it is true as KIMOSABY says my next meal does indeed come from there, must keep "her indoors" happy.

Thanks again folks all the best, John.
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