Dutch Bomb Vessel, Most likely Alvorligheden (Severity)

Jul 22, 2019

Western Colorado, USA
So here's what I came up with for the mortars. The plans all call for 2 100 pound mortars. But 3 different sources I found claim they were built with one 100 pound and one 150 pound mortar. I have 3 plans all of which have the mortar drawn pretty close to the same size, though slightly different. Therefore I'm assuming the drawings are to scale and of the 100 pound mortar as that is what the plan calls for.

So I upscaled the Mortar for the 150 pound mortar using the following assumptions. Basically that it was shooting a solid Iron ball which we know is not correct but I think will still get me in the ball park. I took the bore of the scaled drawing and calculated the volume of the bomb. I then increased the volume of the bomb to 150% of what it was and calculated the radius of the new projectile. This went from approximately a 13.5" diameter for the 100 pound to a 15.5" diameter bore for the 150 pounder. The flaw is of course that the bomb wouldn't be equally dense all the way through, and the larger bomb might not have a thicker shell so my calculation is probably a little small. This is one of those things where figuring this out could be hobby in itself. So I'm calling it close enough unless someone has reasoning as to why I would be way off.

Then I drew up the plan based on how I believe I can actually build a reasonable model of these. I have a Metal Lathe and Mill so I can turn the barrel and mill the base. Then I'll use epoxy putty to hand form the lower portion of the mortar where the barrel connected to the base. I've had success in the past using putty for simple sculpture. I'm more technician that artist but think I can pull it off.

I'm also assuming the larger mortar would be midships. Would be interested in peoples thoughts about that.

Jul 19, 2019

Following your latest drwg. of the mortar I've searched the Danish wbsites but without any useful results. The types of bombs used etc. seem to be very elusive. I've also read the details of the mortar on the orig. drwg. but there's nothing there which could be of help apart from the placing of the mortar itself. A credit to you in working out the (modelling) dimensions of the mortar.

Dave Stevens (Lumberyard)

Staff member
Dec 1, 2016

going through the looking at cannons there are several mortars pictured At least you can see what the look like