Gun ports

Joined
Jul 10, 2021
Messages
1,434
Points
393

Location
Vancouver Island
I'm cutting the gun ports on the Discovery1789. If I measure them off the original drawings they are 24x26.5 inches. I'm going to go with that as the drawing is a primary source. If I look in Steel a Sloop of war(which I have been using for most scantlings) has ports that are 26x29 inches. Swan series ships are sloops of war and they have 6 pound guns, Discovery has 4 pound guns. I'm reasoning that bigger guns need bigger ports. Anyone know of a standard that correlates the two?
 
I guess later in the 18th century they had a standard size for the gunports, related to the type of ship and the used guns.
They defined at this time everything.....

the diameter of the muzzle and the possible inclination of the muzzle, maybe also the recoil should influence the size.

Also defined should be the height of the lower and upper sills, because the height of the carriages of the guns were different.

Until now, all what I wrote is a guess - and should be prooved by somebody or documents / publications
 
I guess later in the 18th century they had a standard size for the gunports, related to the type of ship and the used guns.
They defined at this time everything.....

the diameter of the muzzle and the possible inclination of the muzzle, maybe also the recoil should influence the size.

Also defined should be the height of the lower and upper sills, because the height of the carriages of the guns were different.

Until now, all what I wrote is a guess - and should be prooved by somebody or documents / publications
Hello Uwek, there should be some vintage tables with very specific characteristics regarding the size and material in which a vessel is to be rigged, as well as the openings of the gunboats
 
I found something in the 74 Gunship Volume II by Jean Boudriot.

Off course describing the needs of the usual guns on the french 74 gun ship of the line, but it is confirming my principle suggestions

Unbenannt.JPG

Unbenannt1.JPG
 
Frank, that looks very interesting. I don't read Italian (if it is Italian) but I think it shows English carriages for 1777 and French for 1810. I'm after the dimensions for an English 4 pounder. The chart only has 3 and 6 pounders but it would get me close. If there is a dimension given for the total height given could you write out the Italian phrase so that I can find it. I hope you can understand what I'm asking for:)
 
Last edited:
Here are some pictures of my mock up of an English 4 pounder according to Hahn's little chart. Does everything look right(ish)? Hopefully my final guns will be a little nicer:)

Oops, here's the pictures


DSC04507.JPGDSC04509.JPGDSC04508.JPG
 
Last edited:
Yet another question. In the waist it looks like the gunports run right up to the caprail. Would there be any point in having a lintle in this case?
 
Here are some pictures of my mock up of an English 4 pounder according to Hahn's little chart. Does everything look right(ish)? Hopefully my final guns will be a little nicer:)
you forgot to add the photos.....
 
Frank, that looks very interesting. I don't read Italian (if it is Italian) but I think it shows English carriages for 1777 and French for 1810. I'm after the dimensions for an English 4 pounder. The chart only has 3 and 6 pounders but it would get me close. If there is a dimension given for the total height given could you write out the Italian phrase so that I can find it. I hope you can understand what I'm asking for:)
Got a PM from Frank. Thanks Frank
 
Don,

Just a thought too which is a frequent bugbear in cutting out your gunports (unrelated to your original question about the port’s size), relates to gunport positioning on a frame-on-plank model (POF). With the planks in place and the frames not always visible, cutting into the side of your model can often intersect one of the frames. This becomes a pain when you then attempt to mount your gun carriage as you have to try and gouge out a suitable depth of frame to make space internally!!

Just a note of caution as it’s happened to me…

Regards
PeterG
 
I got lucky. I kinda did an educated guess on the room and space for the frames of the Discovery1789 and when it came to cutting the gun ports 5 out of 7 plunked right into place. I just had to put in a little filler strip on the other two.
 
Sorry to be a year late but this may help someone else.

If you want to be spot-on accurate, purchase the high-res Admiralty Plan of HMS Discovery (1789) here: https://prints.rmg.co.uk/products/discovery-1789-j0509?_pos=2&_sid=80e1c1879&_ss=r Then measure the gunports! This is the best method, far better than any regulations that might or might not have been followed.

Next best to regs are formula.

Not as precise as you would like since it is a generic, but the Ship Model Builder's Assistant, p.229, has general formula for gunport sizing and spacing based on diameter of the shot. E.g., 4 lb shot 3.053" diameter, 6 lb 3.494", 9 lb 4", 12 lb 4.403", 18 lb 5.040", 24 lb 5.546", 32 lb 6.106", 36 lb 6.350", 42 lb 6.684". Ports from center to center should be spaced 25 times diameter. Port length (fore and aft) 6.5 times diameter. Port height 6 times diameter. Sills should be 3.5 times diameter above deck. Thickness of gun carriage sides should be same as diameter of shot and bolts 1/5. Missing, unfortunately, is the sill height which I believe you need to figure the height of the port above deck. Chapman, Architectura Navalis Mercatoria, p.141, has his table for pounds, sill height above deck, height of ports, breadth of ports.

The formula for sill height (the piece of lumber) based on this and an American ship table (differs from the usual), Ship Model Builder's Assistant, p.230, appears parabolic rather than linear.
 
Thanks for the response. It is a little late as I'm into the rigging of the Discovery now :) .
But, J0509 is a "proposed" drawing so it shows in green the changes they planned for the original ship. Note the gunports are green. I don't think the original ship had guns. J2022 shows her 10 years later when she was being changed to a bomb. Again there is red and green ink to show the existing and proposed plans. The gun ports don't quite line up between the two drawings. They vary up to a foot and note that they are not equidistant from each other so they don't follow the "rules" from The Ship Modelers Assistant.
I think I should have followed J2022 as I believe it was drawn from a survey prior to bomb conversion so would be more accurate. When I finally figured all this out it was too late to get them perfect so, if I remember right, I ended up with somewhere in between. You've got me thinking now so I will have to check my work.
Anyway, I wish I had known the SMBA dimensions you gave when I was building this as it would have taken a lot of guesswork out of it. I will double check everything today just to see how I did.
As a little side thing, the fact that all the dimensions depend on the calibre of the shot makes me wonder what they did when they were upgrading the armaments of ships. Did they modify/move all the gunports? That seems excessive.
Again, thanks for the response.

Edit. I checked my work and all but one of my gunports match J2022 and it's out about 6" so I'm pretty happy with that. The gunport size matches the drawing but doesn't seem to match SMBA. The ports seem like 12 pounder ports and the fore and aft spacing is all over the place. It looks like they squeezed them in wherever a bulkhead would allow. :)
 
Last edited:
Back
Top