I've a question about hawse holes shape

[Fam]

Hi all

I have a question about the hawse holes: I’ve just drilled the pilot holes for the 4 hawses in my ‘Brick de 24’ (http://modelshipworld.com/index.php/topic/8675-brick-de-24-by-fam-scale-148-1809-pob/page-3#entry293866), but looking at the Ancre plans I was not able to verify the shape of these holes.

 

I understand that a circle, when seen from an angle, looks like an oval: so all views of the hawse show them as ovals.

I tried some trigonometry, to calculate the height and width of the holes from their projections in the 3-view drawings, but the result is always the same: they are vertical ovals, with height greater than width.

 

So checked on the pictures of the Le Cygne models I have, and also checked the models of brigs belonging to the same class (Cyclope, Esperance, Faune, Curieux): some have circular holes, some have elliptic holes...

 

 

Any suggestion? What is the standard practice? By logic they should be circular, why not being so?

 

Thank you in advance for any help

Fam

[druxey]

They are - or ought to be - circular. Depending on the angle of your viewing a hawse, it may look circular or elliptical. Remember that not only does the hole appear on an angled surface, but the hole itself is usually drilled at an angle. It lies at a downward angle as it goes outboard, and its path was also often slightly curved.

[Fam]

Yeah, druxey,

I suspected this but could not get a confirmation from the drawings... I measured the angle of the hull, then converted the projected horizontal size of the holes (from the lateral view) into the real size, as seen from along the hole axis, using the cosine function of the angle... but the width I got was still 90% of the height.

I will redo the checks, and in case will post here the figure

 

About their orientation, from the measurements I've obtained a longitudinal alignment straight along the keel, and decidedly downward. Hope it is correct!

 

Thank you again for the prompt reply

Fam

[Tadeusz43]

Hi,

On period ships howse holes were round as the anchor cable was pulled to the lower deck through a hole in the hull.
On contemporary ships anchor cable is pulled to the upper deck through howse pipe and howse shape 

depends on the angle of penetration round howse pipe through the shell plating.

 

Hawse holes on :

Jylland  Danish frigate

Sthandard

HMS Victory

HMS Warrior

 

Tadeusz

Edited March 2, 2015 by Tadeusz43

[Fam]

Definitly circularfor ships contemporary to my Brig, thx Tadeusz

Edited March 2, 2015 by Fam

[allanyed]

Fam,

If the drawings show the ship as horizontal, which I assume they are, the vertical height of the hawse hole is also the diameter assuming the hawse holes are round.  Keep in mind Druxey's point about the angle at which you open up the holes.

Allan

[Fam]

Yesterday evening I did my homeworks, and arrived at the conclusion that the plans are somewhat imprecise on this detail, at least in the side view.

Here is the extract of the plans I'm working on:

 

 

The details pointed by the arrows should, in theory, permit to verify the size of the hawse holes. In theory only, because:

• the bow in this position is sloped about 10deg from the port-starboard direction (square to the keel)
• using cosine function on the dimensions taken from the upper figure (front view), the width of the hole is 5.07mm vs a 6.5mm height
• using the sine function on the dimensions taken from the lower figure (side view), the width of the hole is 15.5mm (! absurd!) vs a 6.4mm height

So my conclusion was that the drawing only shows a guideline for localizing the hawse holes but they are not perfectly drawn to size, at least in the width direction.

 

Another consideration from the above comments, which took some time to enter my mind   : when a cilinder (the hawse hole) is intersecting a flat surface (the hull exterior) at an angle different from 90deg, the resulting intersection shape is an ellipse!!!

 

 

So, it is not completely incorrect that the shape of the hawse holes is elliptic on the external hull surface, provided the hole itself is circular in its cross section!

 

But what is the diameter of the hole, i.e. the size of drill bit I have to use? Probably (to be verified), as the axis of the hole is almost square to the hull surface when seen from above, I could consider the width of the oval in the upper drawing (5mm) as a first attempt... if I consider an approximate slope downward of 45deg for the hole, and the hull surface vertical (which is not, but just an attempt!), then  5mm divided by cosine(45deg) makes 7.07mm, that is pretty close to the 6.5mm height measured on the plans

 

Any other consideration or suggestion?

 

Thank you all for helping me thinking!!

Fam

Edited March 3, 2015 by Fam

[druxey]

The hawse hole size is related to the anchor cable size. That, in turn, is related to the size of the ship. Perhaps if you can tell us the known factors, one can calculate or estimate the unknown in this case.

 

Glad you figured out the circle/ellipse paradox!

[Fam]

Thank you druxey

these are the data about the brig size I've found in the monography, related to the Cygne:

 

lenght (transom to stem): 33.50m

widht (hull, I suppose including the channels as the hull alone is 7.50m): 9m

hollow (? "creux" in french): 4.59m

displacement: 537 tonns

main anchor: 1100kg

2nd anchor: 950kg

3rd anchor: 750kg

4th anchor: 330kg

5th anchor: 279kg

 

I know probably it's not enough, but I've found only these numbers with a quick search.

 

Thank you

Fam

Edited March 3, 2015 by Fam

[druxey]

For a ship that size, I think the hawse holes would have a diameter of about 27cm to 30cm. Is that close to what your plans show?

[Fam]

Yes druxey

if I assume a 5mm drill bit diameter in 1:48 scale, it makes 240mm in the real world.

Your 30cm correspond to 6.25mm diameter of the hole in 1:48 scale, so if I drill the hole with a 5mm bit and then finish it with files, it will end up to something between 5 and 6 mm...

 

Fam

[popeye2sea]

You should make your hole diameter 6.4 or 6.5 mm, based on the drawings you have shown above.  The variation in the width of holes depicted in the drawings is due to perpective only.  Notice that the vertical positions of the holes does not change relative to the line of the plank strakes from one drawing to the next.