Serene
Senior Member
[SNIP]
.....a TF member, who posted first in joy and later in great disappointment.
Yeah I can imagine. Nice looking boat, with a disastrous ending!
[SNIP]
.....a TF member, who posted first in joy and later in great disappointment.
That hull bottom looks tender to me.
Reviewing the photos I see the boat has a large electric crane mounted on the aft FB to lift and launch what looks like a RIB inflatable stored there. Wonder if that was taken into account in testing stability?Price was just dropped from $525k to $499k.
Reviewing the photos I see the boat has a large electric crane mounted on the aft FB to lift and launch what looks like a RIB inflatable stored there. Wonder if that was taken into account in testing stability?
Maybe it`s made better, maybe not. Then there`s the build issues of Eliza 1, do they there too?. Not sure about the design layout generally either...rather have my conventional Integrity 386 I think. 2 engines, bowthruster, and I know it`s stable offshore.At the right price, which I am sure it will get to at some point, I am wondering if you cut off the hard top and replaced it with a canvas bimini, removed the sat dome from the mast, got rid of the davit and dinghy from the boat deck, then added a steel shoe the whole length of the keel, plus some ballast low in the bilges, it might be an OK boat...Thoughts?
Maybe it`s made better, maybe not. Then there`s the build issues of Eliza 1, do they there too?. Not sure about the design layout generally either...rather have my conventional Integrity 386 I think. 2 engines, bowthruster, and I know it`s stable offshore.
Thoughts?
Remember Ralph Nadar's book Unsafe at Any Speed, containing a scathing critique of the Chevy Corvair? The coroner's report sounds like a sequel, Unsafe at Any Price. What spooked me was the picture taken bow on in post #103. It could have been taken with a fish-eye lens and that is what makes it look like an iceberg right before it flips over. Filling the bilge with lead and replacing a smaller superstructure with carbon fiber might solve the issue, but so would building a replacement boat.
Question was asked earlier if the roll test metric (seconds to meter of beam) is beam at the waterline. I always assumed that it was and, given the photo shown above, the waterline beam is way different than overall beam. Overall beam on that vessel wouldn't come into play until it was laid on its side. Laid on its side in a boatyard might be the best outcome.
For anyone wanting to get a valid measure of their roll period, get an accelerometer phone app. One can rock their boat and then see what the roll period is over 10 seconds after the rocking force is stopped. Much more accurate than trying to time a single roll. Also download a phone level that allows you to see the angle change in tenths of a degree by adding weight on one side.
Still not sure of the overall value of having these numbers. Measuring heel angle would benefit TF posts because nobody would then say "we rolled 20 to 30 degrees!!!" They would then see that they rolled 11 degrees.
The issue with water flow over rudders in a following sea applies much more to sail than power. Under sail when a wave overtakes you there can be a moment where the water is moving forward faster than the boat, giving poor or reversed water flow over the rudder. On a typical powerboat, there's significant prop wash over the rudder(s), so that doesn't happen nearly as easily.
Very good point. Still given I don’t have a controlled pitch prop have noticed decreased effect when surfing. But you’re right would think it would be circumvented somewhat if I increase rpms. An option not as effective on low powered sail. I was taught to increase rpms going up and decrease going down. That the slower rpms would allow some braking effect and decrease broaching risk. I thought it would be the same with power. I’m a coward and fortunately haven’t been in big stuff yet. What is the correct technique as regards rpm in power when surfing?
For full displacement vessels, if you can't heave to successfully (Delfin can, most power boats can't), towing a drogue to keep you running at a slight angle downwind at 4 or 5 knots provides a safe ride. We are rigged for an Aussie made Seabrake, 300' aft on a bridle. This avoids losing control surfing, and anchors the stern so there is less pushing and shoving experienced. Never had to use it, but a nice piece of safety equipment for ocean crossings.One book to reference would be Dag Pike's "Fast Boats & Rough Seas".
As far as angle to the waves, it will depend on the wave period. The closer together the waves are, the more likely you are to need to take an angle to avoid stuffing the bow. But it also depends on how well the bow lifts when you catch up to the next wave and what it does to steering.
Sometimes the solution is also to just go faster so that the waves aren't overtaking you. Or if the steering is getting too mushy at the top of the waves, it may actually help to slow down a little so you don't spend as long at the top as the waves pass more quickly. Running just slightly slower than the waves are moving is often the worst in my experience.
Given enough power and adequate fuel range, if the seas aren't too huge, there's also the option to just run the engine(s) up to max continuous and outrun the waves (with the bow trimmed a little higher than you'd want it in flat water). You'll slow down as you climb each one, then surf down the faces at a pretty good speed. Best surfing will typically be at an angle when doing this, otherwise you only get very brief surfs before catching up to the next wave. I've done this at times in my boat. With power / trim settings that would give ~17 kts in flat water and 3-ish foot seas, it's common to see the speed drop to ~14 kts while climbing a wave, then surf up to 19 or so. Once while running with the seas about 20 - 30* behind the beam I had the boat up to just over 20 kts (and still accelerating) before we came off the bottom of the wave and started to slow down. My bow is significantly more full (and has much more flare) than an NT though, so your boat may have more of a tendency to dig in.
Most SD or planing hulls will have significantly more beam aft than forward. But if the bow isn't too fine and doesn't dive too deep into a wave, then given enough rudder, it's not much of an issue. You'll get some yawing force as the bow dives in and the stern lifts, but especially at speeds where the bow is being lifted a bit from forward motion, it should remain controllable as long as you're not needing too much rudder to keep the stern in line. Basically, the objective is to avoid sticking the bow into a wave hard enough that you run out of rudder authority to prevent the boat from swapping ends. As long as you can avoid that, you will generally do fine.
Some amount of yaw is also going to be cancelled out as the wave passes under, so you may see a few degrees of swing one way, then swing back the other way as the wave passes. That doesn't necessarily need to be corrected fully on every wave if the boat is tracking consistently and not trying to broach.
Is the MCA methodology better than the USCG?
I get confused but this was Peta Emma I think, the one that washed up at Balmoral Beach(inner harbour) in Sydney from its mooring. Always wondered if its behavior, even on a swing mooring, in strong conditions, contributed to it coming loose.And not a single image of ER (you'd think they'd want to show off the new engine, and show how well the stabilisers were mounted). Still called the "Peta Emma", too.
"And not a single image of ER (you'd think they'd want to show off the new engine,.