Seamaster 40 (oz10212)


Seamaster 40 (oz10212) by Ken Willard 1988 - plan thumbnail

About this Plan

Ace Seamaster 40. Radio control sport seaplane model. Wingspan 59-1/2 in, wing area 725 sq in, for .40 - .45 power and 4 channel radio.

Quote: "Seamaster 40. Designed by Ken Willard.

The Ace Seamaster 40 is designed and engineered to provide you with a nice looking, easy flying amphibian that goes together in a minimum amount of time with a minimum amount of frustration. Please read and follow these instructions to insure that these two goals are accomplished.

We recommend the use of modern cyanoacrylate (CyA) glues for the most part. There are many brands available (Jet, Pic, Pacer, Alteco, Hot Stuff, etc) and they all have three basic viscosities available: thin (for close fitting balsa joints), thick (for plywood, hardwood, and not-so-perfect balsa joints), and very thick (for joints where a filet or 'bead' is required.) For the most part, we recommend the thick variety used in conjunction with an accelerator or 'setter' which cures the glue upon command. Epoxy is recommended for the engine nacelle components. Of course, any modeler has his favorite techniques of gluing but keep in mind that this is a water-going craft and water has a way of getting into everything, so don't use water soluble glues.

There are a few things to keep in mind when building this kit with its lite ply construction. It's a wonderful material that has a tremendous strength to weight ratio and is easy to work. It should punch out of the die cut sheets easily; if not, sand the back of the sheet a bit. Some cutting with an X-acto knife may be needed. Some warping of the material is normal and the key lock construction technique eliminates this being a problem. Also, one side of the lite ply is generally beuer than the other which may have some dark streaks, knots, and fill. Simply keep the good side to the outside of the structure.

We have used various finishing techniques on the prototypes, all of which were successful. Plastic film is the quickest, easiest, and usually prettiest. BUT, keep in mind again that water permeates everywhere so overlap the joints at least 1/4 in and reseal all edges a couple of times to make sure the joints are secure, especially in the hull area. It would be a good idea to go over all the exposed edges with very carefully applied thin CyA.

If you choose to use paint, we recommend that the hull be fiberglassed with 3/4 oz cloth and resin, or cover it with Silkspun or Supershrink Coverite before painting. Avoid too much paint buildup so weight doesn't accumulate.

Although the plane looks bigger, a good .40-.45 two cycle or a .60 four cycle flies the Seamaster nicely; don't be tempted to put a screaming .60 schneurle two cycle on it - the plane is not structurally stressed for it. Realize the Seamaster 40 is not a pattern ship; it is a mildly acrobatic sport ship for pleasing, predictable performance off land and water.."

Direct submission to Outerzone.

Note: Original plan scan by MileHighHerbaFly to RC groups at

Supplement file of Ace R/C kit manual, (complete, 12 pages) thanks to aspeed, found online at

Update 25/11/2020: Added die-cut parts ID sheet, also tracing of landing gear wire pack, thanks to DonShugard.

Update 25/11/2020: Added formers at fullsize. Note this sheet has been scaled up from the very small parts ID sheet, and as such must be used with caution. I will leave this listing tagged as 'formers unchecked' while a better version comes along. Steve.

Supplementary file notes

Parts ID sheet.
Wire tracing.


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Seamaster 40 (oz10212) by Ken Willard 1988 - model pic

  • (oz10212)
    Seamaster 40
    by Ken Willard
    from Ace RC
    60in span
    IC R/C Floatplane Kit
    clean :)
    formers unchecked
  • Submitted: 23/06/2018
    Filesize: 604KB
    Format: • PDFbitmap
    Credit*: MileHighHerbaFly, Circlip, DonShugard

Seamaster 40 (oz10212) by Ken Willard 1988 - pic 003.jpg
Seamaster 40 (oz10212) by Ken Willard 1988 - pic 004.jpg
Seamaster 40 (oz10212) by Ken Willard 1988 - pic 005.jpg

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User comments

Are there no drawings for the bulkheads?
anon - 07/07/2018
This is all we have here. It was kit plan of course. Anyone got more on the formers?
SteveWMD - 07/07/2018
Although we do have two other versions of the Seamaster plan, so maybe that helps. Three, if you count the Seamaster II. Maybe check this one against the others?
SteveWMD - 07/07/2018
Hello, Outerzone. The missing bulkhead drawings from the ACE Seamaster kit plan are not a big issue, since they can easily be drawn from the existing info. The plan shows both the width and height for each station. And we know that the plane has tumblehome sides. However, the horizontal stabilizer is missing and that could be a bigger issue until you know the history. Mr. Willard states in his article on the Seamaster II oz5899 that it is identical to that on his Headmaster Sport 40 oz5877, for which the plan was published in RCM and the design was later kitted by Top Flite. So the solution is simple. That would be the same plan which you have listed, which has the stab.
MatthewStikeman - 30/10/2018
Added nice pic of the completed model, thanks to LucD [more pics 003].
Mary - 21/01/2019
Hi Mary! These are additional photos of the “SEAMASTER-40” [more pics 004, 005].
LucD - 17/08/2019
I have built the Seamaster 40 and the Seamaster 2. The later is a smaller version of the .40 for a .25 size engine. No parts are transferable between the two versions but they look similar.
Steven Swinamer - 28/07/2020
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Download File(s):
  • Seamaster 40 (oz10212)
  • Plan File Filesize: 604KB Filename: Seamaster_40_Ace_oz10212.pdf
  • Supplement Filesize: 290KB Filename: Seamaster_40_Ace_oz10212_formers.pdf
  • Supplement Filesize: 3538KB Filename: Seamaster_40_Ace_oz10212_manual.pdf
  • Supplement Filesize: 776KB Filename: Seamaster_40_Ace_oz10212_parts_ID_sheet.pdf
  • Supplement Filesize: 294KB Filename: Seamaster_40_Ace_oz10212_wire_tracing.pdf
  • help with downloads


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