Seven keel families: recognise shape, ballast and movement

Keel can mean a structural part of a hull or an appendage beneath it. Here catalogue labels distinguish configurations.

Shape, ballast distribution and movement are separate axes. One appendage may have a fin and bulb, lift vertically and coexist with twin rudders.

Instead of seeking one perfect label, describe what photographs and documentation establish. The atlas isolates simplified characteristics; a shared label does not mean identical construction, performance or suitable operating conditions.

Fin and long mainly describe relative fore-and-aft extent; there is no universal centimetre boundary. Intermediate and modified-long configurations exist.

Bulb and wing add information about the tip and volume distribution. A side photograph can hide wings or a second keel, so the atlas adds an end view where needed.

Ballast location still requires documentation: external shape does not reveal every part’s density. A large exterior volume need not contain the mass its appearance suggests.

Lifting keel describes a keel changing position through a documented lifting or other mechanism. Centerboard describes a movable board providing lateral resistance; the name alone does not establish that it contains the principal ballast.

A boat may retain fixed hull ballast and lower a relatively light board, while another has a ballasted movable appendage. Establishing this distinction prevents the Finder equating two designs merely because both can reduce draught.

Raised and lowered dimensions should remain separate, with operating conditions visible.

Lateral resistance, manoeuvrability, drag and stability depend on complete geometry and conditions, not family alone. A moving piece adds components whose condition matters: mechanism, case and access.

A fixed bolted keel and one incorporated into the hull call for different evidence. These differences create no automatic safety or quality ranking.

Ask what is verified, what use the builder allows and what condition the individual boat is in. A model-family drawing cannot answer a survey question about attachments or damage.

Documented examples include twin-keel options in the RM range, moving keels at Southerly, and centerboards and lifting keels at Alubat. They establish that configurations exist without transferring a brand’s marketing assurances to the whole family.

Follow the version with a recorded appendage when opening real-model examples. An inconclusive photograph warrants an unverified classification.

The atlas teaches recognition; a model specification retains evidence. Do not infer that every boat in a range shares the advertised option.