What Is a Keel Clamp and When Do You Need One

September 23, 2026|LMG

BB-06 Ship building jig by LMG holding a hull square

A keel clamp is a support that holds a ship model's keel and hull square and level while the glue sets. You need one any time you're building a hull from a kit or from scratch. It keeps the keel from twisting or sagging before the frames are fixed.

Keel clamp, defined in one sentence

A keel clamp holds the keel straight and the hull level on a base, instead of you holding it by hand or propping it against scrap wood while the glue cures.

Who needs one

Ship modelers building a planked or framed hull need a keel clamp during the earliest stage of the build, before the deck goes on. A hull that sits crooked at the keel stays crooked through planking, so the frames and keel need to be square from the first glue joint. Builders working from bare frames or a keel-up kit rely on the clamp most, since there's no finished hull shape yet to hold things in place.

How it differs from a generic building jig

A generic building jig, the kind used for aircraft fuselages or armor hulls, holds a mostly assembled shape steady while parts are added. A keel clamp does an earlier job: it holds the keel and frames square while the hull itself is still being built up, before there's a solid shape to rest in a jig. Ship jigs like the BB-06 Ship building jig combine both roles, with interchangeable holders that grip the keel at the frame stage and support the finished hull afterward.

LMG ship jig range by hull size

LMG's ship jigs cover different hull sizes rather than one fixed base:

BB-11 Ship building berth mini — for smaller hulls, with supports up to 360 mm apart and holders spread up to 100 mm.
BB-06 Ship building jig — base 250×550 mm, supports up to 470 mm apart, holders up to 210 mm.
BB-09 Sailboats building jig — working field of 750 mm, for hulls up to 750 mm long, with the BB-10 water line marker included in the set.

What comes in the LMG set

The BB-06 set includes the jig base and interchangeable holders, delivered flat-packed and unassembled. Assembly uses PVA wood glue, which is not included. Holders fix to the base with M5 rubber pins, and the same base works across hulls within its support range rather than being cut for one hull only.

FAQ

What does a keel clamp actually hold?

It holds the keel and frames of a ship hull square and level while glue joints set, so the hull doesn't twist during the earliest stage of the build.

Do I need a keel clamp for a plastic kit hull?

Less often. Plastic kit hulls usually mould as one piece. Keel clamps matter most for planked or framed wood hulls built up from a keel.

Can one keel clamp jig fit different hull sizes?

Within a range, yes. The BB-06's base spans 250×550 mm, with supports up to 470 mm apart and holders up to 210 mm; smaller or larger hulls use the BB-11 or BB-09 instead.