Boat length measurement

At the recent boat show in Perth it seemed obvious to me that some boats of the stated same size were bigger than others.

I think from memory chivers and coraline maybe were more generous than some others with boats claiming to be the same size.

With this in mind I have always thought boats were measured at the water line??????????

I guess the reason I am extra curious now is I have been looking at building an ally kit boat, you know the pre cut ones you weld togethor in your workshop at home...

here is one of the options I am looking at. It is a 6.5 metre cat....but is it really 6.5 metres? it shows the total length of the hull to be 6.5 but not the water line. Is this normal or am I right in thinking its probably more like an ohnest 6 metre boat?

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Posts: 313

Date Joined: 18/05/08

external transom

Sun, 2009-08-30 06:51

May be incorect,the external transom isnt included in the lenght of the boat.The bit at the back that ya stic the motor too.

fishy fingers's picture

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Date Joined: 28/04/07

LOA

Sun, 2009-08-30 08:23

Length over all means the total length as in the drawing and with some manufacturers it can also include the bow sprit and platform between the motors as in the drawing (which will be the 7.3m), sometimes they will state the waterline length also which can vary with the design of the hull. If the pod the motors mount on is not part of the main hull (as in mine) then this would not be included in the LOA but if it's a continuation of the hull then it will be counted.

alfred's picture

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Date Joined: 12/01/07

From what I have seen over

Sun, 2009-08-30 09:22

From what I have seen over the years there is no standard. Some include the transom extensions and/or swim platforms and bow pulpit, some don't. If the boat has a bow pulpit as an option, the overall length is usually hull length only. All shipping and pen measurements will be overall length from tip to tip. No one states waterline measurements as the length. Waterline measurements are usually for the go fast folks only.

jersey's picture

Posts: 393

Date Joined: 12/06/08

Alfreds on the Money

Sun, 2009-08-30 13:08

I have even heard of (some) boats being measured around the gunnel,to make them sound more for the bucks,but as far as I have ever thought ,from the bow to stern,(straight line as shown in top picture).is the actual boat,the bow pulpit is an add on in many cases,part of the hull or one bought from a marine shop and attached to help the anchor retrieval,the same applies to the transom some boats have pods added on after,or converted to out board from in board,same as the beam,it is at the widest point as boats tapper from the bow to the stern,although ,some are now as wide at the stern/transom as at the broadest ,to improve stability at rest.jersey

brenz's picture

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Date Joined: 15/06/06

a boats loa(lenght over all

Sun, 2009-08-30 13:53

a boats loa(lenght over all ) is measured from the transom to the bow not including the bow sprit keeping that in mind the transom has to be "part of the hull" not an "extende transom" i used to build for coraline and i can also reasure that genisis and chivers were spot on the pix provided ahow the loa measurement to a t .

Cammos's picture

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Date Joined: 30/06/09

Whatever the length, that is

Sun, 2009-08-30 19:19

Whatever the length, that is a good looking cat.

kane's picture

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Date Joined: 07/12/08

Thanks for the correction fellas

Sun, 2009-08-30 19:30

Its good to get some clarification on that. I have obviously been wrong all these years in thinking it was the waterline length.

Yeah Cammos it looks like a good design, If I go aheasd with this model I was thinking about making the cab shorter to allow more casting / fishing room out the back, the double sink etc doesnt seem necessary to me for the use itll get as a fishing / diving / overnighter at rotto type boat.

Thanks again for all your input fellas

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shammy's picture

Posts: 231

Date Joined: 03/07/09

project

Sat, 2009-09-19 13:32

Hey Kane if you do go ahead make sure you keep us all up to date with how it's going.

It'd be a great read to watch the development of a project like this one.

Damn nice looking cat, and I've only just done my boat up...........

Does the beam of 2.45m put this into the land of overwidth and permits etc??

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PJAY's picture

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Date Joined: 12/05/09

2.5 metre for permits??

Sat, 2009-09-19 14:52

2.5 metre for permits??

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HuggyB's picture

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Date Joined: 03/08/08

no shammy

Sat, 2009-09-19 15:07

And what I think PJAY is trying to say is anything wider than 2.5m is overwidth

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shammy's picture

Posts: 231

Date Joined: 03/07/09

No Permit

Sat, 2009-09-19 16:15

No permit; that makes it even more attractive.

How long /how many hours would you think something like that would take to put together?

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"Life wasn't meant to be a spectator sport"

kane's picture

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Date Joined: 07/12/08

Hey Shammy

Sat, 2009-09-19 18:57

I think i will end up doing it mate and if i do ill definately put pics up to show progress, the only hold up is im in the middle of a home extension as an owner builder so i wont start the boat project untill the house is finished...prob realistically in 12 months time...

Im not totally sure of man hours mate, I work a month on month off roster so would probably hope to get it done in 3 - 4 months off i guess. Being its all pre cut it may be alot quicker than that too but then again its been a few years now since ive done any ally welding too which might slow me down initially.

 

 

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PJAY's picture

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Date Joined: 12/05/09

yup over 2.5m......

Sat, 2009-09-19 17:10

yup over 2.5m......

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The Kimberley....perfect one day and more perfect the next!!!

iana's picture

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Date Joined: 21/09/09

Length of a boat.

Wed, 2009-09-23 15:39

The length of a boat is from the bow to the rear of the transom, (this is where it all changes), and includes any device which adds to the buoyancy.

If you have a pod fitted which is sealed, it is included in the length. My pod is not buoyant so its length is not added to the transom.

 So anything which has no buoyancy is not included.