sunseeker 95

[Bouba]

Erk it is a complex ish thing, but not too bad:

1. First of all imagine the boat with stuck on bits at both ends removed. Remove the bolted on swim platform, the pulpit rail and the nosecone if there is one. Then perform all measurements below on that "stripped down" boat. Some of them might not be relevant, but the nosecone usually is, if there is one.

2. Next take a profile of the boat and draw a horizontal line along the "least moulded depth". On a gin palace motorboat, that is the level of the teak deck in the aft cockpit. Normally the decks will step up along the side decks, but ignore that. Draw a line horizontally that extends the level of the aft cockpit deck all the way to the bow. Red line below.

3. Now measure 85% of the way up from the keel (strictly, the TOP of the keel) to that line (strictly, the UNDERSIDE the deck), and draw another horizontal line at that level. This will usually be a bit above the waterline. Green on picture

4. Measure the length of the boat at that line, "LENGTH A" on picture, and multiply by 0.96. THAT, after the x0.96 multiplication, is the first candidate for LLL.

5. Now measure the horizontal distance from the same point on the bow as above, to the rudder post. "LENGTH B" on picture. There is no x0.96 factor applied to this measurement. This is the second candidate for LLL.

6. LLL is greater of first and second candidates

You can see from this that if you want to make a 95 foot boat qualify as 23.99m LLL you must (a) keep the rudders a little bit forward, though not too much; (b) keep the aft deck as low as you can, but that will conflict with crew space aft and so finally (c) you have to make a removeable nosecone. It can help to make the swim platform detachable and they invariably are but if the 85% notional waterline misses the platform then it doesn't matter

You cannot apply this to all boats perfectly. IPS boats don't have rudders. Some mobos do not have a keel line parallel to the waterline. Top keel is a bit undefined in case of GRP boat. And so on. But most of the time it is a number you can get easily enough on a mobo like sunseeker 95. Its definitely not the plimsoll line.

Wow that is even more complicated than the formula for administrative power to calculate how much boat engine tax to pay the French government
Well done for explaining it

 

[lionelz]

JFM Thanks for that. You can go to top of the class for the day.

All I can say it will never apply to me as I will never be able to spend millions on a boat.

But thanks.

Lionel

 

[Cheery]

Thanks for the explanation JFM. Your graphic explained it very well and it can only be a matter of time before one of the Italian yards snap you up to do their next model!

 

[petem]

Thanks for the explanation JFM. Your graphic explained it very well and it can only be a matter of time before one of the Italian yards snap you up to do their next model!

I don't think Alberto Mancini has too much to worry about .