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Old 03-04-2003, 10:47 AM
Senior MemberCaptains Club Member
Join Date: Nov 2001
Location: Western Australia
Posts: 5,071
Default How much freeboard is enough?

& lodging @ wileys place - now ya talkin!

Just joshin,

Now Freeboard is first and foremostly for keepin the ocean on the outside of your boat (assuming a leaky thru hull or something else don't sink you first!).

The more of it (Freeboard) the better (in as far as doing it's job of keeping the ocean on the outside).

How much is enough?

As a general rule of thumb (as distinct from the dangerous game rule of thumb...which states if the game can eat or stomp you to death then the hole in the end of the barrel needs to be bigger than your thumb! ) you need to have MORE THAN 1/8th the beam in clear freeboard (heres the catch) with your entire rated passenger load all standing at the same time up against one gunnel.

Think about that...

Lets say you got the 31 fountain contender yellafin donzi monza rocketship from mars...and it's rated for say 12 passengers and crew Maximum.

Lets say it has a beam of 10 ft.

1/8th the beam is 15 inches..

so you need 15 inches of freeboard with all 12 folks standing hard up against the one gunnel i.e all the weight on one side.

Well 15 inches aint much BUT you ever seen how much a boat with a real deep V heels at rest, and how easy it heels?

The better rode it is offshore due to deeper V - the easier she will heel over when you put all the weight on one side...

Throw in tuna towers and some wind and fat fella's like me aloft, as well as the rated passenger load all on the one side and some boats tha are considered "very good" offshore fishers might struggle to make the grade as far as the freeboard rule of thumb goes.

It all has to do, with how low the metacentric height of the vessel is (it's righting lever) i.e how much weight is way down low below centre of bouyancy.

This stiff righting lever qualit of a boat is what tends to counteract things like having all the passengers on one side at the one time abnd alspo the tendency for weight aloft in towers to want to roll a boat over.

Yes tall gunnel height can be nice in an offshore boat - you can fish from high gunnel boats easy - all you need is a long gaff handle and long handled net & be prepared to gaff or net everything you catch.

Now swimming a sailfish or marlin bye it's beak to recover it from a high freeboard boat is another thing altogther, and no dounbt a few tagging crew get a swim from time to time from leaning over too far.

So really it depends on the intended useage of the boat and it's design perameters.

Another shortcomming for anglers on high sided boats is that in any kind of a slop - you get a backwash from the sides of the boat that tend to assist your catch to remain just a poofteenth of an inch outside gaffing/netting distance.

I've managed to break the odd fly rod fishing from high freeboard offshore boats, applying just that fraction too much pressure to get a fish withing reach of the gaff / net when backwash from the hull assists the fish to make that last desperate lunge and you got graphite dust for your trubbles!

When the weather turns to crap - your OB's broken down and your drifting on the drogue waiting for help to arrive, and the seas are mounting - you'll be very thankfull for every 1/1000th of an inch of extra freeboard (specially down the transom end where all that water wants to keep commin in.

Thats the time when unsealed walk thru transom doors, cutaway transoms etc lose a lot of their convenience factor value when weighed against purely safety factor.

Cheers, hope this helps.

trouty is offline