dabevan

I have been lookng at Yatchs online and they all quote dimentions etc, but im not sure exactly what they mean by height, do they mean...

1) Height from deck to top of sail

2) Height from water line to top of sail

3) Distance from bottom of keel to top of sail.


...is the definition always the same or do I have to be careful about how 'height' is measured?


Thanks

David Bevan

tigerbay

sometimes a specific hight is given, e.g. mast hight

Otherwise I assume bottom of keel to top of mast.
but you are right, I cannot seem to see a standard either.

LtDoc

David,
There are several ways of measuring height, as you've found out. So, paying attention to exactly what's said is a very good idea. Mast height usually means exactly that, how tall/long the mast is, and is usually measured from the deck. Boat height usually means the mast height and the height of the hull above the water line, sort of. It can also mean from tip of keel to tip of mast. Just depends on how and why it's being stated (more 'pay attention' time). Confusing? It certainly can be - lol! Have fun...
- 'Doc

martno1fan

am i right in saying that mast height isnt what a boats size is measured by anyway ,ie a one metre boat is one metre long .the mast can vary from boat to boat?.id say you measure the mast from deck up.if it says height of mast thats from the deck if it says boat height it could mean from the keel bulb ,yea your right its confusing i need a lie down lol.

Capt Jim

My Feedback: (168)

On "real" sailing vessels, the critcal height is from the water line, up to the highest element of the mast....which sometimes is the radio antenna located there on the top of the nast. It should be specified as exactly what is being measured...you don't want any ambiquity there.
That total height from the water line up is super critical to know...lest you make a very noisy and destructive passage under a fixed (non-opening) bridge.
From the water line down to the bottom of the keel is referred to as the "draft"....or "how much she draws". That too is critical to know so that you do not run aground unexpectedly.
Some masts are mounted (stepped) on the deck, while some others go through the deck and are stepped on the inside of the hull down at the keel. Vessels are categorized by their overall length..."LOA", not their height.
I hope this helps.

Dinosaur

Almost without exception, when someone refers to a specific length boat, it is the length at the waterline. Even in the full size stuff, the dimension they discuss is the length at the water line. This is because the waterline length is related to a concept in physics related to the natural speed of the hull. A typical advertisement will say One Meter RC sailboat, so the boat is one meter long.

If they give the height of the boat, I would assume it is from the bottom of the keel (keel bulb) to the top of the mast. If they give mast height, it will be the height of the mast from the attachment to the boat to the top of the mast. Another interesting figure is the sail area, usually reported in square inches (or possibly square centimeters I guess). There are even classes that are reported in two numbers, NN/YYY. The NN number is the waterline length and the YYY number is the number of square inches of sail area. This permits development of new designs rather than "One Design" classes. I prefer one design racing. Builders often prefer the other system.

Capt Jim

My Feedback: (168)

I would respectfully disagree with Dinosaur regarding how a boat length is specified.
True, theoretical speed of a displacement hull through calm water is approximately 1.2 X the square root of the water line length. However, waterline length will always be much less than LOA..."Length Over All", and is virtually meaningless when speaking in terms of hull capacity and true size. Additionally, manufacturers will always want to appear to be offering a larger boat, and so their literature will always advertise the longest figure possible....which is typically the length on deck as a minimum, but sometimes will be the length from the most forward tip of the bow rail, to the aft most tip of the stern rail. Dockage in a commercial marina is rated by dollars per each foot of boat length. Dont ever get caught trying to under pay a dockmaster for overnight dockage in a marina by giving him the waterline length. It just isn't billed that way, and you will be branded as a cheat.
Once again...height is from waterline up to the top of the mast.....critical to clear under a bridge.
Draft is from waterline down to the bottom of the keel. Critical to keep from running aground.
Those are the two absolutely vital statistics of all boats, and these are the specific measurements that any boat captain knows exactly, as they relate to his boat.
Any other dimension is of lesser importance and will be specified only with regard to a specific unique situation.

Spdsk8er

My Feedback: (3)

wow capt jim. although right, that was confusing[&:] but yes, he is ture, and you are wrong. (no offense) LOA also includes lifelines, and stuff. it is always measured at the deck.