70ft 9in British Power Boat Company MGB 1942 1:48th Scale

[Steve D]

As I've been promising, this new thread follows on very quickly from the MTB, it is intended as a companion model and will cover the larger BPB boat before the addition of torpedo tubes.  I've been working on the drawings while competing the MTB and so here we are ready to start building.

 

For those who are not familiar with the type, this illustration from the Osprey British Motor gunboat publication gives a great idea of what the model should end up looking like

 

 

I've managed to source about 10 high quality images of this class on-line, here are a couple of the better ones, MGB 75

 

 

and MGB 107

 

 

I've searched hard but can't find any commercially available model drawing sets, but the Haynes workshop manual featuring MGB81, the historic preserved MGB, is a great source of information and contains two extremely good drawing sheets that scale rather well and provide accurate lines.  I've been able to scan, re-align and re-scale these and had them printed as A1 pdf's.  They are based on drawings held by the IWM archive and to my delight, a number of the builder's drawings have been scanned and are available to purchase as art prints.  Screen grabs of these provide useful back-up information and additional detail which is great. 

 

As It seems a shame that commercial model drawings are not available, this time, I really intended to completed a model markers set of plans that others could use.  I'll make these available at both 1:48th scale and 1:72nd scale, more on that at the end of the build.

 

The model will be 18 inches long, a nice size to work with.  Here are some of the refence material I'll be using, the pdf reproduction of the Haynes drawings included below

 

 

I'm not sure I should post a copy of the Haynes manual drawings here, but as a teaser, here is one of the IWM art prints you can buy (full size copies of original drawings, would look great framed)

 

 

So, overall I'm happy there is enough detail for me to build a decent model of these vessels, one of the key criteria for me to start a project.  If you are wondering why I've included the Anatomy of the ship Fairmile D book, it actually has the best drawings of the twin Oerlikon power turret which was shared with the dog boats.  The Vickers 2prd turret on the bow is identical to that fitted on the SGB so I've already built one of those and have the etching drawings of the mount, the props look the same (as far as I'm concerned) as the MTB, I have a 3d model of Holman projector and the right smoke machine so this should be easy eh...

 

I didn't have a drawing of the twin Oerlikon, but I do now 

 

 

This, together with the 2 pdr and the props are being cast by Shapeways and should be here in a couple of weeks, the guns in brass and the props in bronze, £80 for all 5 pieces inc shipping.

 

So, progress to date, I've re-drawn the times and checked the gunwale, and chine alignments, that Haynes manual drawing is really good..  The whaleback deckhouse was slightly off, but I used the IWM construction drawing to correct it, think I have it right.  Here is my outline lines drawing, the starting place for the frame drawing.  On interesting point is the outer rudders are angled at @10 degrees to the vertical, that's a little challenge to get right.  

 

 

For this hull, I'm reverting to balsa infill hull construction which is then covered in diagonal planking.  The MTB wasn't a great success in my mind as the inner curvature of the lower hull really didn't work well because the planking had no intermediate support.  Also, the simple balsa infill I used on the S-boote actually leaves you able to see the frames in some lights which is bad.  This combination approach should solve both these issues, it is what I used on the Fairmile B but that all happened before I started posting so I'll cover this in full detail here.

 

This sectional drawing shows how the hull and deck house will be constructed. The deck-house top box stringers are deliberately composite as they curve in 2 directions and a single piece of wood would be too stiff and might actually warp the hull.  The chine stringer is horizontal to allow the balsa blocks to be slid in, I'll show all this in the build.  The vertical slot in this frame at the top is there to receive the open bridge side piece which connects frame 6 and 7.  Frame 6 was moved forward a small amount to form the forward bulkhead of the open bridge, details details....

 

 

A new thing I'm trying on this project is the two locking bars, we'll see if they work.  As I've said before, bent hulls are not good and using 1.6 mm ply for a keel is easily bent by the gluing process.  Before I've dropped the deck-house into an open box structure on the lower hull and this box helps keep everything straight.  With this whale-back deckhouse which curves in 3 dimensions, that isn't possible (well anything is possible, its just not easy) so I've drawn two side bars in the plan which will (I hope) slot through all the frames and then slide towards the keel to lock them and the frames in place to make sure it is all straight.  Stick with me and you see what I mean

 

From the lines above, each frame then needs splitting out, re-drawn to allow for the outer planking and the slots set in for the longitudinal timbers.  The result is the following cutting plan, locking side bars at the bottom

 

 

This was then turned into cutting artwork (colour changes and re-grouping) for cutting from a 1 ft x 2ft sheet of 1.6 mm ply (I just love mixing units, keeps the brain active...).  2 days later, this arrived in the post from 4D for a very reasonable £55, I'm getting so lazy in my old age...🧑‍🦼

 

 

Add some balsa from SLEC and strip-wood from Cornwall Model boats and you have a wooden hull kit in the making

 

 

The outer planking will be done in pear wood, it will look fantastic and be such a shame to paint it...

 

Build starts tomorrow

 

Cheers

 

Steve

[Faraway]

@Steve D

Permission to come aboard ?

I do like these boats, so will be watching her come to life.

Jon

[Dmitriy1967]

Hurray! New build from Steve D ! I am happy to join you. I will follow with interest.

Edited March 2, 2022 by Dmitriy1967

[robgizlu]

Classic and Beautiful (obviously the boat not you Steve )

And all curvy

Hooked - as usual

Rob

[Jamie @ Sovereign Hobbies]

Nice one. I'll watch this quite willingly

[longshanks]

Great to see you tackling one of the lesser known boats 

 

Kev

[PAUL67]

I’m in for this one too Steve..as for being lazy in old age your just working smarter mate…

Paul

[Iceman 29]

A new season starting, you are insatiable! 😜

 

A good beer and a sofa to follow it all. 

[S-boat 55]

I shall follow unless you object, 

[Steve D]

Everyone is most welcome to join this little adventure, let's see what I can mess up this time 

 

I love the long whaleback deck house and the way the deck dips to the bow, such interesting lines.  As I may have said before, sanding a wooden hull gets you an appreciation of a ships lines that drawings cannot convey, probably my favourite aspect of this hobby.

 

Thanks for the support and nice comments, sit down and strap in

 

Cheers

 

Steve

 

[JohnWS]

Cool, Steve!

 

I've been fascinated by the British Power Boat MGB's & MTB's.  Very different in many ways from the Vosper boats.  I'm looking forward to following along.

 

John

[Steve D]

25 minutes ago, JohnWS said:

I've been fascinated by the British Power Boat MGB's & MTB's

Thanks John, I've been through your BPB MTB build thread, great scratchbuilding and fantastic finish, something for me to aim at 

 

Cheers

 

Steve

[Courageous]

Gotta love a coastal craft build. I'll take a pew.

 

Stuart

[beefy66]

Another interesting subject your knocking them out at some pace there Steve will follow along with the rest of trouble makers,  

 

Stay Safe

beefy

[Steve D]

Frame build-up, first the good news, the slot cutting allowances were fine and everything fitted really well, even my sliding locking bars worked as I'd hoped, I may just be getting better at this stuff...

 

However, I made three stupid mistakes. 

1. I forgot to leave a cut-out for the twin Oerlikon mount in the whale-back spine
2. The cut-out for the open bridge back frame was out by the thickness of the ply (1.6mm).  Looks like I chose the wrong side of the line to offset, dumb.
3. The rear angled rudder support frames were slightly too long, again by the thickness of the ply.

But these are all easily fixed by cutting away, only my pride took a beating.  The picture below shows the two areas on the keel that needed cutting, I've amended the drawing as I will for any other errors I come across

 

 

The first job after the trial fit is to install the brass guide tubes.  There are three of these in the keel, one to take the rod support for mounting the boat on pillars, one for the central prop tube and one for the central rudder (2mm prop tube, 2.34mm for the rudder guide and mounitng rod).  These were cut and epoxied in place.  The masking tape allows me to centralise these tubes in the ply which of course is thinner.  The cut-out adjustments have been made in this picture

 

 

Then the open bridge box is made up, the floor is out of 1 mm ply

 

 

This shot of the frames in place shows where the box sits.  It also shows the horizontal locking bars.  These are threaded through the frames once they are slotted down on the keel and once in place, they slide across to touch the keel on both sides.  Thin cyno quickly fixes that in effect making the keel into a cross shape with all the frames locked in place and right angles to the keel, straight and square.  This stage worked a dream 👍

 

 

More thin cyno later and all this structure is solid

 

Next the two angled rudder shaft tube support frames have their own rudder support tubes glued in place and then (after a slight length adjustment) glued in place and to the transom which is kept square by these frames and some scratch bits of angle ply stiffening.  Note the transom has pre-cut holes for the exhausts which will have etched outer flanges and bolt detailing (I've started a list of the etched components I need, but I guarantee I will forget something....)

 

 

The outer prop shaft tubes have also been glued in place and in alignment.  I'm not sure if this detail is right but I aligned the outer prop shafts on the same angle as the rudders which seemed logical and good engineering practice as otherwise there would be a slight lateral force on the rudder.  Its a shame that the lines drawing doesn't include the horizontal shaft alignment, they often do but not in this case so I had to work from a section showing the rudder alignment only.

 

I don't know if this is all too much boring detail.  I wanted to fully explain how this little wooden hull comes together in-case any of you want to follow me and build one to this design.  I'll be happy to supply the cutting drawings or even cut sheets and printed items to make things easier  #getintowood

 

Cheers

 

Steve

[Adm Lord De Univers]

2 hours ago, Steve D said:

 

I don't know if this is all too much boring detail.  I wanted to fully explain how this little wooden hull comes together

 

No, no, no, not too much detail, not at all. And definitely not boring, but quite fascinating!

 

David

[Courageous]

I agree with David. Always nice to see the different ways to 'skin a cat'. With the exception of a few faux pas that I believe were deliberately put in to show us your fallible side, you're off to great start.

 

Stuart

[stevehnz]

Way to go. I've long liked the look of the early BPB boats, more rakish, dare I say sexier than the Vosper boats & one of these is a hole in my collection of kits to make, so I'm along for the ride for sure. The plans sound like a great idea too.

Steve.

[Steve D]

12 hours ago, Courageous said:

I believe were deliberately put in to show us your fallible side

Stuart, that's my best side, the infallible side is a right bore

 

11 hours ago, stevehnz said:

one of these is a hole in my collection of kits to make, so I'm along for the ride for sure

Welcome aboard Steve, just let me know if you want to follow with a build of your own, two is always cheaper than one

[stevehnz]

9 minutes ago, Steve D said:

Welcome aboard Steve, just let me know if you want to follow with a build of your own, two is always cheaper than one

Its a nice thought Steve but it's very much a one day when I retire & catch up with myself a bit thing, & that isn't going happen very quickly of that I'm fairly certain.

Steve.

[Modelholic]

Makes me wish I'd picked up one of the 1/72 'Coastal Craft' kits when I had the chance.

Oh well.

I'll follow along!

Tom

[Steve D]

13 minutes ago, stevehnz said:

it's very much a one day when I retire & catch up with myself a bit thing,

Shame, would, have been fun.  The problem I have with retirement is where to put all the blxxdy models....

[Faraway]

2 minutes ago, Steve D said:

Shame, would, have been fun.  The problem I have with retirement is where to put all the blxxdy models....

And that’s one of the reasons I moved to building ships ! 
They are long and skinny, so take up less room than aircraft. And of course they are more interesting. 

Jon

[Jamie @ Sovereign Hobbies]

16 hours ago, Steve D said:

Frame build-up, first the good news, the slot cutting allowances were fine and everything fitted really well, even my sliding locking bars worked as I'd hoped, I may just be getting better at this stuff...

 

However, I made three stupid mistakes. 

1. I forgot to leave a cut-out for the twin Oerlikon mount in the whale-back spine
2. The cut-out for the open bridge back frame was out by the thickness of the ply (1.6mm).  Looks like I chose the wrong side of the line to offset, dumb.
3. The rear angled rudder support frames were slightly too long, again by the thickness of the ply.

But these are all easily fixed by cutting away, only my pride took a beating.  The picture below shows the two areas on the keel that needed cutting, I've amended the drawing as I will for any other errors I come across

 

 

The first job after the trial fit is to install the brass guide tubes.  There are three of these in the keel, one to take the rod support for mounting the boat on pillars, one for the central prop tube and one for the central rudder (2mm prop tube, 2.34mm for the rudder guide and mounitng rod).  These were cut and epoxied in place.  The masking tape allows me to centralise these tubes in the ply which of course is thinner.  The cut-out adjustments have been made in this picture

 

 

Then the open bridge box is made up, the floor is out of 1 mm ply

 

 

This shot of the frames in place shows where the box sits.  It also shows the horizontal locking bars.  These are threaded through the frames once they are slotted down on the keel and once in place, they slide across to touch the keel on both sides.  Thin cyno quickly fixes that in effect making the keel into a cross shape with all the frames locked in place and right angles to the keel, straight and square.  This stage worked a dream 👍

 

 

More thin cyno later and all this structure is solid

 

Next the two angled rudder shaft tube support frames have their own rudder support tubes glued in place and then (after a slight length adjustment) glued in place and to the transom which is kept square by these frames and some scratch bits of angle ply stiffening.  Note the transom has pre-cut holes for the exhausts which will have etched outer flanges and bolt detailing (I've started a list of the etched components I need, but I guarantee I will forget something....)

 

 

The outer prop shaft tubes have also been glued in place and in alignment.  I'm not sure if this detail is right but I aligned the outer prop shafts on the same angle as the rudders which seemed logical and good engineering practice as otherwise there would be a slight lateral force on the rudder.  Its a shame that the lines drawing doesn't include the horizontal shaft alignment, they often do but not in this case so I had to work from a section showing the rudder alignment only.

 

I don't know if this is all too much boring detail.  I wanted to fully explain how this little wooden hull comes together in-case any of you want to follow me and build one to this design.  I'll be happy to supply the cutting drawings or even cut sheets and printed items to make things easier  #getintowood

 

Cheers

 

Steve

 

This to me is the most interesting part of modelling. I lose interest quickly with fine detailing. It's making 3D shapes out of raw materials that interests me, and I enjoy seeing how different people approach this. Carving shapes out of a solid block interests me the least out of that particular subset of modelling techniques, whilst forming shapes from a network of 2D profiles interests me most

[Dmitriy1967]

6 hours ago, Steve D said:

 The problem I have with retirement is where to put all the blxxdy models....

 

I read a book once when I was a kid. It told about an old man who lived alone on the riverbank. He made toy ships, put good wishes written on a piece of paper in them and sent them down the river. Ships sailed all over the world. And every person who found them had the old man's good wish come true.