Issaquah 130s

[zman]

Now that Bremerton has the Sealth instead of the Kitsap, I have been able to look around and see how much space the second car deck takes up. That is alot of weight that has been added to the vessel.
Anybody know how the 130s are able to keep the same depth in the water with all that added weight?
It seems like the 130s should sit alot lower in the water than the 100s.
Did WSF reduce weights in other parts of the vessel to compensate?

[Barnacle]

Not that I'm aware of... the Issaquah class has a very broad hull--the nautical equivalent of a fat butt, which is also why it pushes so much water aside when it moves. There's a lot of displacement down there.

[chokai]

At first I was thinking that the vessel specs on the IFBs could be considered fairly definitive given the risks posed from a dry docking mistake such as hitting or washing out the blocks. Then I saw this in the contracts for the Sealth (06) and Kittitas (07):

Sealth: 15'6" (2,477 tons)
Kittitas: 16'6" (2,475 tons)

Interesting.... Now sure how that would work.... Were the boats originally ballasted in some way and had it removed at a later date? That wouldn't explain the draft though.

The WSF site says the same, but I wonder if this could be a typo of course, or if the boats are ballasted. Steven's site is the same.

I agree with zman though, I would think that a foot difference would be notable though when looking at the boat.

[Barnacle]

Well, first off, you'd have to get two of them side by side, which doesn't happen often.

Second, the 2477/2475 figure you mention is gross tonnage, which is a volumetric measurement. Deadweight tonnage (or displacement tonnage) is the actual weight of the ship. If they specify that somewhere in the contract, we'd be getting somewhere.

Third, removal of ballast from down low in the hull to compensate for adding weight up high, above the center of gravity, has the same effect as moving the weight up higher on the stick of a metronome. The tick slows down and it takes longer to get from side to side (roll period). If the stick of said metronome were extended up for a larger distance, eventually the weight would get high enough to tip over (capsize) the metronome, unless you added weight (ballast) to the bottom (keel). Consequently, removing ballast would probably be about the last thing they'd do when adding the ramps.

All that having been said, the Sealth's wings look positively cavernous, don't they? We can (and frequently do) load small overheight vehicles out there. In fact, mentioning this reminds me... the Sealth is allowed to carry three lanes' worth of talls on board, versus the two lanes the other five are allowed. I do believe that's where a lot of the extra weight you're all trying to remove came from.