Ocean-Going Catamaran Size and Bridge Deck Clearance

[jcb47769]

I crossed the Atlantic in a cat 2 years ago (they wrote us up in Cruising World) and I had 2 conclusions. First, bridge deck height is REALLY important. I had a Nautitech 54, built more towards the racing crowd than cruising, so she was equipped about the same as a Lagoon 44 in terms of gear. Quite high bridge deck, and she took the waves very well. We had some seas that Lagoon or Fountain-Puejot (sp?) would have been unable to handle. Second, weight is important. Don't get a 35' cat and load her up with gear, she'll lose all her speed. Best bet for safe crossings (in my opinion) is bigger and lighter load. There comes a point where you lose the ability to plane properly, and as such lose all the advantages of a multihull. Hope this helps

[StuM]

Cruising cats don't plane.

[tolly]

Well, first of all, if the owner can't tell you the correct building year of the boat there must be something wrong, since a boat of that size should be registered and thereby have all data. Starlight in UK is 1986 model and narrow, and my Portugeese friends 1990 model is wide, so somewere between these years the change was made. Just beware of the few boats built just in the change, since they had bad reputation of some reason.
Correct beam should be appr 6.1m, which is a little more that 1m narrower that the later Quasars. The lower bridgedeck clearance on the narrower ones is partly compensated...by its narrowness, since you get 1m less width of building waves underneath bridgedeck. At least that's my thought. My friend in Portugal, that for several years had the wider type, claimed that it "allways" slammed when in waves, even though it had more clearance than my narrower type. The slamming is inconvinient in the salon if you have galley up (which we prefer) and if you are sitting there eating (which we seldom did during sailing anyway). In the forward beds I installed alu crossbars with a plywood sheet on, raising the beds appr 50mm from the under deck hull, which totally got rid of the slamming there. Besides that I don't feel it's a major problem, since the boats are built to cope with it.
Bottom line is that I love this type. It's not as large and high inside as the more modern catamarans, it doesn't sail as fast as many of them, it has an old fasion style inside, with the darker wood, it has rounded hull sides making it look like a racer without being it...and it has a lot of personality.
People I talk to who are curios about catamarans, use to tell me that I sound fanatic...and I reply that I'm not fanatic, though convinced. That's an important difference.
Good luck in your decisions.

[SearenitySail]

FWIW,

Another discussion of bridgedeck clearance by Pete Melvin (Morrelli & Melvin) and Simon Slater (Alan Slater's son --PDQ catamarans):
Bill Springer's Boat Blog: Catamaran Tech

How important is bridgedeck clearance? Melvin: It all depends on how you plan to use the boat. Bridgedeck clearance is not as critical on smaller coastal-cruising cats that don’t go too far out into the big bad ocean, but on offshore boats that will be subjected to big seas, higher bridgedeck clearance is essential to minimize pounding. We look for bridgedeck clearances on cruising catamarans to be between 4 percent and 6 percent of the length of the boat off the water. This height simply makes it easier for waves to pass harmlessly between the hulls rather than pounding up underneath the bridgedeck. As well as having suitable bridgedeck clearance, a cat should have underbody surfaces that are relatively smooth. Slater: All cats will pound from time to time, especially in steep chop. The critical design factors to consider to reduce bridgedeck slamming are bridgedeck clearance, rig weight and height, bow shape, and keeping the weight out of the ends of the boat. The combination of these factors in correct balance will give a much smoother running boat and give far greater levels of comfort. As anyone who’s experienced catamaran pounding can attest, it’s an unpleasant, nerve-wracking experience. Higher bridgedecks reduce pounding. Less pounding is faster, minimizes structural stress, and, most important, makes for a much more comfortable ride. It should be realized that the designed height of the deckhouse and topsides will be relative to the bridgedeck height, so it is important to balance “sleekness” against the consequences of insufficient bridgedeck clearance.