85' ARB by Melissa T. - Scale 1:32 - POB - First Scratch Build

[Bob Cleek]

Before anybody buys an airbrushing rig, I strongly suggest they read the thread linked below.  Pay particular attention to Kurt Van Dahm's comments at post #7. Kurt is MSW's airbrushing expert, as far as I'm concerned. (And it appears the Badger airbrush company shares my opinion!) I expect if you send Kurt a PM, he will be able to recommend something that best meets your needs at your chosen price-point. Note also that I believe the MSW sponsor, USA AIRBRUSH SUPPLY, offers discounts to MSW members. 

Your 85' ASR build looks like it's coming along very well. I have a bit of first-hand familiarity with this family of "crash boat" vessels. There were several around San Francisco Bay "back when" and at least one of the 85 footers is still afloat and operational on the S.F. Bay and Delta waters. See: Testimonials (homesteadcloud.com) They were quite popular with the Sea Scouts, who apparently were at one time able to get them for nothing as government surplus.  A friend of mine's father skippered the Air Force ASR stationed at Hamilton AFB in Novato, CA on S.F. Bay as recently as the late 'sixties or early 'seventies.

 

The widespread misconception that the hulls of the PT's, ASR's, and similar small craft built in WWII were built of plywood deserves to be dispelled. Plywood was used in the construction of flat surfaces in these boats, such as decks and bulkheads, but not in their curved hull surfaces because their hull forms contained compound curves (where curves go in more than one direction at a time in the same piece of material.) Because the plies of plywood are laid in different directions, plywood can only be bent in one direction and is not suitable for developing compound curved shapes. The wooden hulls of the WWII production small craft in question were built with multiple layers of traditionally spiled planking fastened together with glue and mechanical fasteners, the compound curved shapes being developed in the lay-up of the planking layers. This is a much more involved construction process than simply nailing sheets of prefabricated plywood to a frame. 

 

All of the 85 foot ASR's were double-planked with a layer of canvas laid in waterproof adhesive between the planking layers. The inner cedar planking was hung at 45 degrees to the diagonal, 1/2" thick below the chine and 7/16" thick above the chine. The Honduras mahogany outer planking was hung horizontally and was 3/4" thick below the chine and 9/16" thick above the chine.  The inner planking was fastened to the longitudinal timbers with bronze screws and to the frames with copper nails. The outer planking was fastened through the inner planking into the frames with bronze screws. The inner planking was then fastened to the outer planking with bronze screws from the inside. The decks were 3/4" fir plywood, fastened with Monel ring-necked nails to the deck beams and with bronze screws to the shelf and clamp. The decks were canvas laid over white lead paste. The 85 footers were decidedly not planked with plywood because their hull shapes included compound curves which are not possible to develop. The planking was finished "fair" (smooth) as might be expected, so planking and filling your model hull with a sanding filler and then painting will permit you to use wider planking stock as you have used on the bottom, but I would expect that the graceful curves of the bows will be more easily developed with narrower planks than you were able to use below the chine. 

 

If you haven't come across it already, you will find the "U.S. Crash Boats" website a goldmine of information on the entire "crash boat" and "Air-Sea Rescue" class with specific information on the 85' ASR's. This site provides more information than I've ever seen on this type of site. It has PDF's of all the applicable manuals, design and construction details, and even extensive crew lists for all of the crash boats. See: 85 ft. Army Air Force Rescue Boat (uscrashboats.org) See also for a large number of interior and exterior detail photos highly useful for scratch modeling: Boats: Crash Boat, Aviation | Flickr .

 

 

Edited December 31, 2023 by Bob Cleek

[Melissa T.]

Thank you, Bob for a lot of useful information!  I'm very familiar with the crash boats website, and have been in contact with the gentleman who runs it.  That's where I found the operator's manual for the 85' ASR, learned about the mahogany planking, etc.  I will definitely check out the Flickr site

 

And thanks to everyone for your kind comments and good advice on airbrushes - much to review and think about!

 

Melissa

[Bob Cleek]

Funny coincidence. I happened to see this book listed in the WoodenBoat Store book section: Crash Boat published in 2021. It apparently recounts the exploits of the ASR's in the South Pacific. I thought it might be of interest to you if you haven't come across it in your research as yet.  See: Crash Boat: Rescue and Peril in the Pacific During World War II: Jepson, George D.: 9781493059232: Amazon.com: Books (Shop around, it may be available for less elsewhere. Apparently available in both hardcover and paperback.)

[Melissa T.]

Basic hull is mostly complete, minus some more sanding down to 600 grit and the rub strakes that I still have to make. Amazingly, it actually matches when I lay it on top of the plans, so I’m happy with it! Someone in previous posts mentioned using shellac, and I wanted to ask about that.  What shellac, or other product, could I use to seal this hull and fill any remaining cracks in the wood grain?  I would want to be able to sand again after applying this product, and then ultimately airbrush with an acrylic primer and then paint.  Thanks in advance!

 

Melissa

[Roger Pellett]

Since you are gong to paint the finished model, why not just spray it with a pigmented primer.  This will highlight and allow you to deal with all sorts of blemishes that you will not see with a clear coating such as Shellac.  This first prime coat is sacrificial. Once you have filled blemishes and sanded the hull there should be very little left.  You can repeat this prime/fill/prime process until you are happy with the results.

 

If you use a water based primer (many acrylics are thinned with water), it will raise the grain in the wood creating a rough surface.  That’s OK because you are going to sand the primed surface anyway and the water’s effect on the grain will disappear after a few applications of primer. 

 

Fillers:  To a large extent, the primer will fill the grain, but you will need some sort of filler to fill nicks, planking gaps, etc.  Everyone seems to have their favorite.  Mine is Durham’s Rock Hard  Water Putty.  This can be found in hardware stores.  It comes as a powder to be mixed with water so you can mix it to different consistencies.

 

Roger

 

 

[Melissa T.]

Thank you Roger!

[Dr PR]

Melissa,

 

On some of mu older (50+ years) models I had problems with the wooden planking swelling and shrinking with humidity, age, whatever. This cracked the paint on the hulls.

 

I started using a thin clear epoxy paint on the interior of the planking. Model airplane builders use this paint to seal balsa engine mounts so fuel cannot soak into the wood. I apply a fairly heavy coat so it will seep between the planks and between the planks and the bulkheads. It does soak into the wood surfaces, and when it hardens the hull is very solid. I have hulls 35+ years old that have never developed cracks.

 

I mention this because you are at the right stage to paint the interior - before the deck goes on. Not many people do this, but at least one of best model builders on this site use it inside planked hulls. You won't have to worry about the hull planking cracking years down the line if you do this.

[Melissa T.]

Interesting, and I may try that!  Here’s where I am right now, after four coats of Rust-oleum automotive primer and a lot of sanding. I used the Durham’s water putty to fill cracks, etc, which was an excellent suggestion. Have also drilled a few holes for exhaust and bilge. Traveling for the next couple of weeks, so I won’t get back to it until late in the month.

[Roger Pellett]

Wow!  Hull looks great!

[Melissa T.]

Thanks Roger, and thanks for the recommendation of Durham’s putty. I had never heard of the stuff. I like that I can apply it with my fingertips and that the excess sands off easily.

[Jim Lad]

That hull's looking really good, Melissa.

 

John

[Melissa T.]

Thanks, John!

[Melissa T.]

Traveling quite a bit last month, so not too much progress though the hull is now complete with rub strakes, rudders, etc. Turning attention now to deck and pilot house.

[Rick310]

Looking good!!

Rick

[KeithAug]

The hull has turned out well. Planking when the frames are widely spaced is quite tricky but you seem to have made a success of it. Well done.

[Melissa T.]

Thank you!

[Jim Lad]

She's really coming along very nicely, Melissa!

 

John

[Canute]

Nicely done. She looks fast.👍

[Melissa T.]

Work proceeds steadily, albeit very slowly. Hull and deck painting are complete, for which I did a lot of research on paint colors used in the CBI. Can’t say I enjoy using an airbrush, but it’s necessary for this kind of project.  The superstructure is next, which will be extremely challenging (for me, at least) due to its many angles and curved surfaces. Working on the .50 cal gun tubs now, for which I used a couple of PVC couplings in the right size as a mold to bend 1/64” plywood around.  I have found it is difficult for me to envision the two dimensional plans and photos as a three dimensional object, so I have adopted as a best practice making everything in card stock first to see how it looks and fits before cutting any wood. Onward!

 

[Jim Lad]

Very nice paint job, melissa. It's a good idea to use mock-ups in card if you can't easily visualise an object from the plan. i think it's important to know what something looks like before you build it.

 

John

[Roger Pellett]

Really nice work Melissa!  The deck structures can be tricky on these small craft as they often slope.  This means that a conventional three view (orthographic) drawing provides a distorted view of the shapes.  While there are manual drafting techniques and of course CAD that can provide a "true view,"  modeling in cardboard will work too and of course then you wind up with patterns.

 

Roger