Bulbous Bow applications

[GuestR01312011]

Probably not for a 50fter cause all the extra weight of the mechanical system would not be good for trim or pitch frequencies, but yes I think on a tanker or something it would be plausible, dunno why it hasnt been researched. maybe cause its easier just to set a design speed say 25kts and assume that the tanker would make its journeys at this speed give or tak a knot, this is usually true, but for something like a warship/coastguard vessel it would improve the power efficiency but ALOT of research would have to be done, cause if its designed wrong the power eff. would drop rather than increase.
You also have to take into account the most efficient RPM for the deisel, therefore its more efficient at a designed RPM therefore speed therefore no point in having a varying RPM throughout the voyage.
Are you Irish?

[juiceclark]

No, Scottish. {cheap} I originally got the idea because I saw Nordhavn had designed a 70' sportfish model with a 4,000+ mile range.

http://www.yachtforums.com/forums/no...yachtfish.html

All their models over 60' have a BB...except this sportfisher. I assume that's because it wants to run a little faster?? It's such a different design for them I couldn't help but wonder why their usual models couldn't be made sportfish-style.

The boat I'm building is all about economy. We're hoping for 7 miles per gallon at 9 knots while having the ability to plane at 20k. So, a BB was clearly something to consider if it didn't screw-up planing. The best fishing in the Gulf of M. off Sanibel Is. here is 120 miles out. So, a boat that would be perfect for a slow, nighttime cruise to the grounds was my goal. Getting back home is pretty important too!

Because of the beamy 17.5' at the transom for a 46' boat, my next thinking will be about breaking suction under all the flat surface. I'll bet you guys have some awesome suggestions about that!

Tony

[juiceclark]

Originally Posted by Alan Mikkelsen

PS, don't be fooled by the twin dry stacks. This boat is single engine, wet exhaust. He wanted a place for a chest freezer, so he built what looks like a stack topside, with twin 'pipes'. The pipes are actually black PVC, but they serve to ventilate the compartment that holds a chest freezer! He will run a small Honda generator a couple hours a day and it stays cold with no problem. He has a large Onan generator below, in the engine room, but it sees little use.

I took the generator out on my 40' sportfish and have two 2K Honda portables instead. With 1000 pounds less weight, (genny, fuel tank, exhaust, etc.) They stay safely in a cabinet! I never run the A/C at sea anyway. With the plug that combines them, 4K is enough for anything. I run one on the dive platform (so quiet)plugged right into shore power if the banks start to get low.

Alan, I greatly appreciated your BB contribution. If you'd like to share anything about you Dad's stern-work to break suction I would luv to hear about it!!

[yipster]

many bulb bow threads but i like kach22i bulb foil fantasy sketches
here the sweep bulb design that sucks in the wave ( see page 11 )
without the bubble it reminds me a bit of this sucker doodle i drew

[kach22i]

Originally Posted by yipster

many bulb bow threads but i like kach22i bulb foil fantasy sketches
here the sweep bulb design that sucks in the wave ( see page 11 )
without the bubble it reminds me a bit of this sucker doodle i drew

NOTE: Hover your mouse over the pages to see C11, counting the page sheets is not the same for some reason.

Nice magazine.

[yipster]

hmm, hoovering to C11? dont see a problem but copied the sweep bulb bow pic below