But you can sail at 15-20 degrees off dead down wind and sail faster than the wind speed. You boat speed adds to the apparent wind speed. This makes it looks as though a fast boat is sailing close hauled when in fact it is pointing almost dead down wind.
That’s true; but it’s such a radically different design that I can’t see any good reason to conclude that they’re comparable.
We can exceed windspeed downwind, and Bayesian is probably faster. SailGP, MOD70s, and those huge ocean racing 130ft tris can do nearly 2 x windspeed, at 150-160 degrees. I don’t understand what you’re saying here.
If the winds are say 20kts, the boat might make say 9 kts with 11kts of apparent wind. If the vessel can make 18kts (hull speed or thereabouts) under power and that is what is the passage plan is based on, then they need the engine.
I think what we have to remember is that if the weather event is a supercell, the wind will be very localised. Had the cell gone a few hundred metres one way or another, the MAIB might well have had to commission a report into the stability of the Sir Bayden Powell. Since we don’t know what the windage of the SBP, there is nothing to compare
I don't have experience of sailing a 50+m boat. The one person who I've seen comment that actually does have experience said the above in an interview. Unless you have such experience then nothing changes as far as I'm concerned. I do know that boats can sail off the wind. I also know that most doing a transatlantic don't bother and tend to drift with the wind and tide because they have better things to do than actively sailing the boat. I also know that commercial vessels with a schedule and a huge fuel tank will tend to motor if it's easier. Fundamentally he said it was easier to motor because they had the range in the tank and the boat doesn't sail well downwind due to LWL. He also said he felt bad for the boats half the size without the range of diesel but with the downwind issue. I believe him, he has after all actually sailed the boat.
Presumably that’s cruising under power. Very likely it could sail faster than motor. I thought these type of boat was capable of 20kn plus in the right conditions. Otherwise, billionaires would be embarrassed at being overtaken rather often these days.
It absolutely was, all superyachts are one way or another. It's extremely rare for the skipper to just sail about with the owner for fun.
I didn't. The interview is available on YouTube (I think cruisers podcast?). The vessel's cruising speed is irrelevant, there isn't significant resistance until approaching hull speed and that means the boat will accelerate easily downwind up to the wind speed, making apparent wind zero until the boat slows again. We've all experienced this, so I'm unsure why anyone with more than five minutes experience doesn't intuitively understand it.
with the LWL of these hull speed is about 18kt from what I can tell. I've no idea if the accepted formula scales that big though, a lot of things seem to work differently at such scales.
Have you actually done a transatlantic crossing? Loads of boats doing things like the ARC “tack downwind”, ie zig zagging to get the best apparent wind angle which maximises the Velocity Made Good downwind.
From the first line of the MAIB Narrative: "privately owned and operated yacht".