Sailboat Guide Definitions

Hull Type

Board Boat - A sailboat that does not have formal seating, typically you sit on the side decks and there is a area in the center (footwell) that you put your feet.
Day Sailor - A sailboat that has seating, but does not have a cabin that you can sleep in. Some of these have small cuddy cabins that you can put stuff in. Also I include small dinks and tenders in this category, even though their only seat is typically a board across the middle.
Pocket Cruiser - A sailboat up to 20 feet long which has a cabin and a door that you can go inside, and a bunk to sleep in.
Multihull - Any size sailboat that has multiple hulls, such as catamarans, trimarans, proas etc.


Length Over All. Typically this is the length of the hull itself, and does not include the length of the rudder or bow sprit.


This is how wide the boat is across it's maximum width.

Weight / Ballast

The Weight, in American Imperial pounds, is the total boat weight including the ballast. The ballast weight is only how much the ballast portion is. For smaller boats, sometimes the factory specifies a weight of just the hull which does not include the rigging weight. On those types of boats, the rigging is usually fairly light so it probably doesn't matter.


This is the number of berths or bunks that the factory intended for you to sleep in. Personally I have often slept in the cockpit and some cabins have places that can easily be converted into an extra bunk, but I don't count these.

Draft Up / Draft Down

How deep the water needs to be to sail an empty boat. A boat loaded with crew and extra gear will sit lower in the water, so would need more draft. The up dimension is with the keel retracted. The down dimension is with the keel down. In cases of a fixed keel, it only has the up dimension which reflects what the depth of the fixed keel is.

MIC (Manufacturer's Identification Code)

All boats manufactured (or imported) for sale in the USA since 1972 have been required to have a standard 12 digit HIN number (Hull Identification Number), the first three letters are the manufacturer's MIC code. The HIN number is required to be displayed on their hull in 2 locations, the first location is for public viewing and is on the stern transom in the upper starboard side. The second location is somewhere concealed, incase the main one was damaged or intentionally vandalized. Sometimes this second one is easy to find, and sometimes it is hidden on the inside of the liner or other location that you normally don't access. The regulations are shown here and here. Below are some example HIN numbers.

Date Conversion Codes
January A
February B
March C
April D
May E
June F
July G
August H
September I
October J
November K
December L
Sailboat Full HIN Manufacturer
1974 Scat ASN000550974ASN 00055 0974
1977 Hobie 16 CCMF1624M77DCCM F1624 M77D
1980 Oday 19 XDYC0157M80CXDY C0157 M80C
1982 Vagabond 17 VAGA03110882VAG A0311 0882
1983 Laser ZFSA9818M83BZFS A9818 M83B
1986 Holder 12 CCME1489F686CCM E1489 F686
1986 Laser 2 TDA05831F686TDA 05831 F686

Character 1 through 3 are the manufacturer's MIC code, so you can lookup who made the boat. Here is the us coast guard MIC database Please note that because there are only 3 letters, they ran out of combinations and some of the codes have been reused. Usually they have a note who owned the MIC previously.

Character 4 through 8 is the serial number that the manufacturer assigns to the boat. Most of the times it seems to be just numbers, for instance the Scat below is 55, meaning it is the 55th hull produced. But in cases where they have produced lots of boats, the manufacturer's seem to use a combination of letters and numbers.

Character 9 through 12 are the date the hull was manufactured. In the case that it is 4 numbers, then it is in the month year format (MMYY). If it is a combination of letters and numbers, then the numbers are the 2 digit year, and the letter represents the month as shown below. I have read that the regulations have changed over the years, but can't find the previous regs. In the date examples above, I can't figure what the M is supposed to mean. Anyway, the year it was made is pretty clear, so thats good enough for what we usually are looking for.

If you build a sailboat yourself, or if you register a boat that was built before they were required to have the standard number, then the state you register in will assign you a HIN for your boat. The format is a bit different, the first 2 letters are the state, then a "Z", so it you are registering a boat in Texas it will be TXZ..., then the state will assign the middle numbers and the final numbers will be the year they think your boat was made. I registered a boat I knew was built in 1968 from the factory brochures, but the guy at the registration office said he was pretty sure it was a 1970, so tacked a 70 on the end of that number. Guess doesn't matter, that number makes everyone happy and I got my registration. I then used an engraving tool to etch the number into the stern in the proper location.

SPID Number

This is the ShortyPen ID number I assign to a boat. Often I get information about a boat and the name isn't exactly correct or turns out it is completely wrong. I organize the boats by ID number so I can update the name when I get corrected information. Also I have some mystery boats listed, and when we discover the name of it, can update the listing with it's correct name - so it makes it really handy to have my own ID numbers for each of the models.

Keel Types

Daggerboard Sailboat


It is an unballasted board that goes vertically (or maybe diagonally) up and down. It does not pivot, just goes up and down through it's trunk. The board made be made of various materials like wood, fiberglass or aluminum, but it does not contain weight intended to be ballast (help with righting the boat).

Centerboard Sailboat


An unballasted board that pivots down. The board may be made of various materials, but does not have weight intended to help right the boat. Some boats have the centerboard over on the side, and some have 2 centerboards, these are labeled as just centerboard boats and I don't have a seperate category for those.

Fin Keel Sailboat


It is a board that sort of dangles off each side of the boat. You lower the one on the lee side, and raise the one on the windward side. For factory boats, the most prominent example is the Sea Pearl 21 shown in the picture to the right.

Although it is commonly viewed as strange today, this is the earliest form of a keel (lateral resistance). Leeboard of various types are very common in home built sailboats, see

Swing Keel Sailboat

Swing Keel

Its a big and heavy centerboard that pivots down. The weight of the board forms some or all of the ballast which is used to right the boat.

Dagger Keel Sailboat

Dagger Keel

Same as a daggerboard, only it is a ballasted board that drops down. A good example is the Holder 20 or Potter 19.

Shoal Keel Sailboat

Shoal Keel

This is a short keel that is fixed to the hull and has a fixed depth. The keel doesn't go the entire length of the hull. Some of them have a centerboard inside the keel that pivots down such as the Montgomery 17.

Fin Keel Sailboat

Fin Keel

A single keel that goes deeper than a shoal keel. Sometimes the fin keel can be really skinny and deep, sometimes with a bulb on the end to keep the ballast at maximum depth.

Fin Keel Sailboat

Wing Keel

Its a fin keel with a wing down on the bottom. Sometimes it looks like a plate on the bottom, sometimes like little aircraft wings.

Full Keel Sailboat

Full Keel

This type of keel is fixed and extends the full length of the hull.

Twin Keel - Bilge Keel Sailboat

Twin Keel (aka Twin Bilge Keel)

Two fixed keels underneath the hull. Typically they are short keels and allow the boat to sit uprigth when no water is under the boat. Great for tidal areas where they are moored and the water runs out leaving them sitting on the bottom.

Tri Keel (aka Triple Bilge Keel)

Similar to the twin keel, a tri keel has three keels under the hull and they are also intended for the boat to sit on the ground upright.