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Modification Information for Building a P5M-1 Marlin from the 1/72 Hasegawa SP-5B

Updated: Dec 27, 2022

Consult photographs of the P5M-1 you are modeling for the modifications needed. Note: Kit part C22 (Step 11), ECM Direction Finding Antenna (Doghouse) above the cockpit, may or may not be used depending on photographic evidence.

A special thanks to Bruce Barth of Martin Seaplanes Historical Research (, the preeminent expert on the Martin P5M-1 and -2 Marlin. His research, consultation and documentation has been invaluable for verifying the accuracy of the P5M-1 Conversion Set and this information.

Portlight or Window behind and below the Cockpit:

The round window on the Starboard (right) side is in the correct position. The round window on the Port (left) side needs to be moved back to the next panel.

Aft Waist Compartment Observer Windows:

From 1952-57 there were no observer windows left and right side at the Aft Waist Compartment. After Aircraft Service Change ASC-439 (1957-1959), the Navy added observer windows to 22 P5M-1s BuNo 135452-135473 and there were 7 US Coast Guard P5M-1Gs with observer windows. The P5M-1G was redesignated P5M-1T when returned to the Navy in 1960 and given BuNo 149825-149831.

If modeling a P5M-1 prior to 1959, Glue clear parts E6 onto Fuselage Assembly (see Step 8) and use filler of your choice to fill seam and sand flush. I prefer thin and gap filling super glue (cyanoacrylate) and sanding within 15 minutes before the glue gets too hard. Paint over window when applying paint to fuselage.

Aft Fuselage:

Early P5M-1s from 1952-1957 had two 20 mm guns in the rear/aft end of the fuselage. Cut flat and modify kit part C13 for ball faring. Some had the guns removed, but the housing remained. Some P5M-1 and P5M-1Gs had a smooth ball fairing. After 1957, use kit parts C13 and clear part E3 (Step 9).

Left (Port) Bombay Nacelle:

Use the shallow, symmetrical 3D printed bomb bay and front for the left (Port) side engine nacelle for P5M-1 prior to 1959 and for USCG P5M-1G. Use the kit parts C2, D18 and D19 for the deeper bomb bay after 1959.

Aft Waist Compartment Hatches:

All P5M-1s had an Aft Waist Compartment Hatch on the left and right sides near the crown of the hull at the leading edge of the horizontal stabilizer. The modeler may want to scribe the hatches and reposition and lower the portlight to center it in the hatch.

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