I seem to be several years late on this, but I just saw this info today. I was in River Section 512 in 1967~1968. At that time we were driving MK I PBRs. The MK I was a great boat, but suffered greatly if a normal weight load was exceeded. We used to carry about 800 rounds of .50 cal aft, and 2000 forward. My Engineer (who used the M60) carried about 3000 rounds. We also carried 3 M16’s, 2 M79 40mm Grenade Launchers, a shotgun, and personal side arms (typically 9mm, .45 ACP, or 357 magnum. The Navy issued all of us M14’s when we went in-country, but mine stayed locked away until I departed and turned it in. We always had plenty of weapons around. Anyway on the boats we sometimes mounted a MK18 Honeywell hand crank 40mm Grenade launcher over the aft .50, but frankly it was a sensitive piece of gear and gave us too much trouble, so it eventually fell into total disuse. On occasion we’d take a 60mm Mortar to throw H & I fire. We set the base plate into a cut off 55 gallon drum full of sand. We experiment with carrying a 90mm recoilless rifle, but due to the back blast problem that was unwieldy and we abandoned the idea. We also experimented with a mini-gun, but because of the loss of speed from excess weight we couldn’t carry enough ammo to make having it fruitful. For that same reason I have a hard time believing that a 20mm would be installed anywhere on a PBR. At least on a MK I. The added weight from 20mm ammo would have been devastating to speed and maneuverability - the key safety items for any PBR. I’m not saying it didn’t happen, just that in my 18 months I never saw such a thing. If it was tried I can imagine that it was a one off trial that went away when it was discovered how much operational performance suffered.
The 20mm was only fitted to Mk II PBR,. It was actually a resurrection of a WWII design that was developed for Elco PTs, where 20 was mounted to the gunner’s right. The WWII version could mount both the Hispano-Suiza or the Orlikon (the thinking being that the boat crews would use either the aircraft or th ship cannon based on local supplies were available at forward basing).
The VN edition only mounted the Orlikon on the right, and a 8" searchlight to the left.
In both cases, the weight of ammo was the problem
The other install that never quite panned out was using the 81mm/cal…50 combo mount. The problem there was not being able to see targets in the minimum range envelope of that 81 (and a PBR not being a good “repeatable” platform for registered fires). Add in the problems of storing the heavy 811 ammo, and the loss of flexibility on the .50 and it just was not worth the penalties.
What is your source for this, please? In five decades of PT research, I’ve not come across any mention of such a mount. The only 20mm turret mount with which I’m familiar is the MK12, which was a purpose-built mount used on a number of boats in RON 9 .
I can imagine the weight problem. Carrying a fire team (5 men) of ARVN on a MK I cut our speed by probably 40% and maneuverability by more. Even with the bigger impellers on the MK II I would imagine a big performance drop when armed with enough 20mm or 81mm to be useful. Thanks for your input.
Hello!
Lots of nice and valuable info here. PBRCAPT - do you have any photos of the Mk. I that you could share with us? They would help meny people with their models. Mk. I photos aren’t so easy to come by.
I bought a set of Mk. I plans some time ago and was contemplating cutting down the Tamiya model to make one, but still need to do some research.
Thanks for sharing and have a nice day
Paweł
Hello Pawel:
Because the hull configuration of the MK II is so different (low profile) I almost think you’d be better served to take those plans and just start from scratch with basic materials. I’m guessing that that would be much less trouble than trying to modify a MK II kit. I’ve always wondered why no one put out a MK I kit. It’s like the MK I was lost in history. I do have pic’s of varying quality and all black and white. I suppose I could scan them to digital then try submitting to the gallery here. I’ll give it a go and see how they look. Also, if you Google related words - Operation Game Warden, TF116, PBR, etc. you’ll find some veteran’s sites that have pictures. But I caution that mostly they’re of MK II’s. The MK I shots I’ve seen are generally poor quality, but may be worth your while. Anyway I’ll try the scanning. Keep an eye out, it’ll take me a while to get it going.
Quite a few years ago, Karl at Microglass put out a 1/32 scale MK1 hull in fiberglass. He may still have the molds. www.microglass.net
Al Ross
Oh wow!!! I checked Microglass and they have a MK I kit listed as a standard product. I bought one immediately. Will advise how this turns out once I have hands on and can evaluate it. Thanks so very much for the tip.
Thank you Al. I’m interested too.
Roger, that. Here are some much-reduced images from my 1/12 scale set of plans for the MK1:
(http://s73.photobucket.com/user/alross2/media/mk11.jpg.html)](http://s73.photobucket.com/user/alross2/media/mk12.jpg.html)]
(http://s73.photobucket.com/user/alross2/media/mk13-1.jpg.html)]
Al Ross