Scale Model Vosper MTB?

[NickPasch]

I am crazy about PT boats of various ilk. Elco, BPC, Vosper; it doesn't much matter, I think they are all great. I was expanding my 1/72nd collection recently, since I have been know to splash a mold off of a small scale boat, and I ran into an oddy. I purchased a Revell (Germany?) "British Vosper M.T.B." . This boat /can't/ be a Vosper boat, circa WWII. The most fundamental characteristic of the varous wartime MTB's from Vosper is an essentially flat transom. This boat has a distinct "V" transom. It further has twin machine gun tubs side by side in a way that Vosper never had, that I can trace. I am becoming convinced that the model is of a Thoneycroft(sp?) boat, rather than a Vosper boat. I wonder if Revell approached the current company Vosper-Thoneycroft and asked to reproduce one of their WWII boats, and were handed the plans for the Thoneycroft PT boat? From the looks of things, I am pretty convinced, but I wonder if anyone has also seen this boat and has any ideas. If there are any scale boat people out there, I would appreciate any help.

Nick

[AndyKunz]

I think I have plans of a Vosper hydrofoil from WWII. It was a V bottom.

From Walter Musciano, published in an Air Trails 1951-1957 or so. I will have to look to find it if it's really important to you.

Andy

[twmaster]

Andy,

If he is not I am interested in Hydrofoil plans!

I too like PT and other patrol boats like Coast Guard and such. I have a growing collection of hulls. Nice to see I am not the only one :)

[NickPasch]

Thank you, Andy. I'm still trying to sort out the Vosper 70', 72'6", 73', Brave Boarder, Simitar, Perkasa, and Soulvin classes, I think my brain would pop over a hydrofoil. I have figured out that I am not building another wooden boat until I have done a glass boat. My PT-109 took months to scratch build in wood, paper and dope, and I'm not going to do it again real soon. I was told that it is possible to actually /buy/ a hull that is ready to finish. Sounds pretty heretical to me, but I got sooo tired of wood dust up my nose.

Thanks again,
Nick

[AndyKunz]

There are several glass hull companies you may want to talk to. At least one of them is in CA.

Andy

[HyperBaja]

i have a 19' baja ( full sixe boat) and have been wanting to get a rc model of it for years, would you be willing to build the hull? i can get pics form every angle, and measurements.
thanks
tommy

[eddieh]

mike/nick/Andy, you guys are not alone, my first rc boat was a dumas pt 109, (talk about heavy) anyway I still got it, I have been trying to convert it to a "Nasty Class" pt, when I get the chance I will finish it someday, I have now fitted three shafts and was planning on using 3 400's on gear drives, I do have some really good plans for a bofors single mount from fine scale modeler, if anyone is interested (1/35 scale) cheers eddie

[NickPasch]

Hi Eddie,

I have also looked at the conversion of a PT to a Nasty class boat, but I ended up going a slightly different direction. The Lindberg 1/32nd PT-109, does not have a very authentic hull shape. Because they knew that their model was going to come in much too heavy, the Lindburg people spliced in an extra 2 cm of width to the transom, to give the model more displacement. It fixes the problem of a model that will come out too heavy, but provides a wonderful opportunity to make a Nasty hull. From a normal view, the Nasty has three major differences from the PT:
1) The transom is wider on the Nasty. Lindburg solved this problem for you.
2) The keel of the Nasty is rounded at around the 30-40% station. Since this is normally under water, I'd be willing to let it slide.
3) The chine line of the Nasty has an odd dog-leg at about the 25% station, a kink that offsets the chine line upward on the hull leading to the bow. The chine line on the Lindburg PT is not all that well defined, and you could reproduce the dog-leg without it looking too odd on the Lindburg hull.
Bottom line was that it seemed like a pretty good start to a Nasty class boat.


The Dumas 1/30th scale is about 80 ozs with one motor and battery, instead of the 54-67 ozs it should be. Definitely a porker. I seem to have discovered the same Speed 400 Race (4.8) and gear drive for multiple motor installations. Looks like a sweet package, without too much weight and just the right power.

I did a calculation on the 1/48th scale PT-109 hull from Microglass. Looks like 5 X 1600 AA NiMH cells, a Speed 400 Race (4.8) and a 2.3:1 gear drive with an X430 is just about perfect. Have to try it some day soon. If you have a 2.0:1 gear, just use an X427, but remember, there isn't a X427R, while there is an X430R, in case your gears reverse the rotation of the prop.

I'm looking at a 1/72 PT made of balsa and tissue just now. I figure I'll just scale the 1/32nd model Glenn Guest designed for Model Boats (UK). It is looking very promising with 2X 750mah Li-ion batteries, a DC6 - 8.5 coreless motor and ~ 2:1 gear drive. More news as events warrent.

Best Regards,
Nick

[eddieh]

Nick how much bigger would the 1850 li ion batts be??? the kind generally found in laptop packs, I have played with these on and off, the problem is the charging? propshop uk actually has 4 blade counterotating props if you want true scale, I actually believe that pt boats in general had 3 left handed props, no counter rotation? but I could be wrong (wouldn't be unusual) I have two lindberg hulls in the bone yard as well as the dumas, so I'll have to do a bit more research, good luck with your project, cheers eddie

[HyperBaja]

with three left hand, prop walk would be a crazy amount! with a single weed eater engine in my scarab, it has so much that i have the rudder turning 10deg to the right and 45 deg to the left and it barely turns left but spins out on the right turns!!!!
go with 2 left and one right, should balance out better.

[vicman]

Hey hyper,
Torque steer is not always a problem with multiple drives, With twins it can be a real pain in the neck, but with triples thats not always the case. I have built a couple triple drives including steerable triple drive and the torque steer seems to be less of a problem on them (even less on the steerable drives) than it is on the doulbels and singles. I have found that the distance between the props and angles of the prop makes a big difference on how bad the torque steer is. I havent found a formula to figure this out , all been trial and error. This is obviously only my own experience and more opinions would be helpful. Your suggestion would definately be a great help to keep it straight, but it is all going to come down to whether the right props can be found in left and right hand rotation. There is a pc of the steerable triple on this board, search under "scratch and build" boat name "spirit". The hardest part is going to be getting the angles right so they all are in the water working with each other. I cant wait to see how others do and if they are much different from mine.

vicman

[HyperBaja]

i always wondered why those tripple engined 1100hp each Hustler superboats always stayed so strait? must have good angled trim.

[NickPasch]

I haven't considered the 1850 Li-ion battery at all. I suppose I should look to see what the properties are, I may be missing a great deal, especially for slightly larger scales. The trick with most of my boats is weight control. The 1/72nd PT has to come in at about 116 grams for a scale weight. Not that easy to do if you figure that the batteries, esc, and motor shouldn't be more than about 35-40% of the entire weight of the boat. I can't see any NiCd or NiMH battery pack that can come in on weight. That said, the hard current limitations of Li-ion batteries makes the choice of motor pretty tough. And we are not even going to talk about the charger system.

I have also discovered that the BPB 60" ASR hull in 1/72nd scale can be perfectly powered with a DC 5-2.4 motor, 2X 450mAH Li-ion batteries, and a gear drive. Who would have thought that you can get completely (dynamic) scale performance with such a small hull (90 grams)?

I originally was working with glass and epoxy hulls in 1/72nd scale, and I had pretty good luck making the hull, but I am finding that the deck edge-hull seal is a lot tougher to make water tight that I thought, and makes for a pretty heavy hull, at least the way I do it. Considering that I am allegic to wood dust, building with balsa isn't the easiest decision. I assume that vacuum forming a hull will not get me a strong enough and light enough hull. I particularly want to avoid internal frames that have to be had fitted.

Nick

[vicman]

Link is from a thread about Ebay (you know how that'll go). I guess it answers the question of torque steer and prop rotation. Not TOO fast but looks awsome.Quad drive (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1766494864)

[eddieh]

Originally posted by HyperBaja
with three left hand, prop walk would be a crazy amount!
Hyper the real boat 1 to 1 scale didn't have counterotating props I have often thought about the same problems you have mentioned to do for a model, I wanted to convert my chris craft 63' motor yacht to three props but have never done so because fo the same thoughts you had, but maybe I'll give it a go, cheers eddie

[HyperBaja]

didnt know that the chris crafts went up that big. do you have any smaller boats? i have a 19 baja, and am planning on buying a 13 catamaran with a 50hp on the back this spring...

[eddieh]

Hyper, sorry, I should have said model, but chris craft did go that big for the 1 to 1 scales, they were some of the first super boats!!! there was a cat awhile back called the jesse james I think was a chris, not sure , but I couldn't begin to think what a chris craft 63' motor yacht would go for these days, the sterling kits are going for astronomical prices, sorry about not being clearer

[HyperBaja]

no worries

[Vlad-sr]

To Andy and Mike. I am interested about that hydrofoil plans very seriously. But I am “second in the line”, so I would like to know, what happened that plans. Let me know please. I have plans for hydrofoil to, but it is build like sport shallow Vee aero boat for .15 nitro. But scaling or changing is possible.
Vlad

[Vlad-sr]

Nick, did you see Vosper Perkasa from Pegasus models or Germen torpedo boat from Harbor models or Model ship building site Vietnam patrol boat? You are not alone crazy about torpedo boats. I have PT video clip on picture gallery under video & pic.
Vlad

[twmaster]

I am going to start building my Danvo PT-65 this week and I have been gathering some nice 1/35 scale goodies such as cannons and ammo crates from the Tamiya plastic kits. I am hoping to have a Lindberg 1/32 landing craft built sometime soon too :)

Also on the list of craft to start/finish:

Dumas 41' Utility Boat
Robbe Lehmar P1000
Tamiya 1/350 Tirpitz