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Rick wrote:
No props. A set of Kamewah water jets. If you want to quibble, the water jets substitute impellers for propellers. In some cases they are harder to access too, but in general they're less troublesome IMHO... just like a big pump... in fact that's what it is. The trade-off is that they're less efficient at low speed because the intake velocity gives the impeller/nozzle a boost just like apparent wind for a sailboat. I don't know from my own experience, but I've heard it said that they don't give as much kick for maneuvering at low speed, but don't have prop walk so that's good. One of the interesting water jets I saw was on a 21' light trailerable sailboat. The water jet came out the back through an extended nozzle about 4" above the water line. Fresh Breezes- Doug King |
DSK wrote:
If you want to quibble, the water jets substitute impellers for propellers. In some cases they are harder to access too, but in general they're less troublesome IMHO... just like a big pump... in fact that's what it is. The trade-off is that they're less efficient at low speed because the intake velocity gives the impeller/nozzle a boost just like apparent wind for a sailboat. I don't know from my own experience, but I've heard it said that they don't give as much kick for maneuvering at low speed, but don't have prop walk so that's good. No need to quibble, much less troublesome. Lots of "kick" at low speeds since they accelerate a huge weight of water in a very short time and put it anywhere you want it. Twin jets and a bow thruster are lovely. The OP specified a 150' boat, rapid reversing capability, and precise speed control ... all the attributes of jets in a boat that size. Efficiency is not the highest rung on the ladder in that installation. Rick |
Rick wrote:
No props. A set of Kamewah water jets. Rick Also, not a bad way to go. Since money no object, use computer controls and a "joystick" for handling options .....just watch out for "nasties" sucked into impellers. |
In article , Joe
wrote: (Peter Wiley) wrote in message om... (Joe) wrote in message . com... Peter Wiley wrote in message ... In article , Capt. NealĘ wrote: Aluminum is relatively worthless for a boat hull. All it takes to completely destroy the hull of an aluminum hulled vessel is a handful of mercury past smeared on it. It will begin to turn to dust within hours, break apart and sink. A stainless steel boat is impervious to just about anything but strong acids. Bwahahahahahahaha. It's obvious you know SQRT(f**k-all) about metallurgy. S/steel is not a good metal to have in continuous contact with seawater. My biggest objection to aluminium is that its abrasion resistance is low compared with steel and its ultimate failure point is too close to its deformation point. Steel is a lot more ductile but does require good barrier coats to keep rust at bay. If money is no object, you build out of cupro-nickel. PDW Whats cupro-nickel? And why? I hear nickle copper is best, the copper is a perfect antifoulant. http://www.technicalmaterials.com/me...ro_nickel.html Same stuff, just you got the name wrong. Look it up in Lincoln's welding handbook and you'll find that you can weld it with MMA using ECuNi rods, good weldability. Ditto for GMA welding, GTA welding and fair welds using carbon arc tho why you'd bother is beyond me. Preheat not required, no fancy techniques needed unlike aluminium or s/steel. Good mech properties. Pretty much inert so no real corrosion probs and as you noted, naturally antifouling. Real problem is the price. Friend of mine's brother is a scrap metal dealer, got 2 tanks of Inconel one time for the price of s/steel. Wish I'd have known him back then, I woulda bought them off of him and saved the sheets for a hull. Yeah that would have been a great find. We have lots and lots of chemical and petro plants around here, If i ever feel like building a new hull. It would be nice to never have to deal with the hull again. Read about a 32 footer over in england called the Pretty Penny. Hauled it for the first time after 20 years with no noticable loss to the hull, a layer of slime and grass that was easy to simply brush off. But guess it all depends on the price per sheet. LME has copper at $3246/tonne, nickel at $14255/tonne. 70/30 cupronickel, call it $6500/tonne. A Q&D calc gives me approx 0.3 cubic metres of metal in an 11m hull of 4mm plate thickness so that'd be 0.3 * 8.9 (Cu is 8930 kg/m3, Ni 8800 kg/m3) * 6500 = $17K for the hull plate. Minimum since this makes no allowance for cost of rolling etc etc. You might be able to afford it but I can't :-) PDW |
Rick wrote:
.... Lots of "kick" at low speeds since they accelerate a huge weight of water in a very short time and put it anywhere you want it. Twin jets and a bow thruster are lovely. That does make sense but I've head a couple of people say that jets will not give as definite a push when gunned at low speeds as will a conventional prop. If you look at it as a problem in differential pressure, it seems to me a pump & jet nozzle could generate higher delta-P much quicker though. I guess to make sure I'll have to try it for myself some day. I have driven a couple of small jets, the biggest one a 25-ish foot center console... heavy boat, flat bottomed, badly prone to side slip but a lot of fun in the shallow water it was designed for. It had a fixed jet nozzle & conventional rudder. The OP specified a 150' boat, rapid reversing capability, and precise speed control ... all the attributes of jets in a boat that size. Efficiency is not the highest rung on the ladder in that installation. Yep. People that are mega-rich have different priorities! Fresh Breezes- Doug King |
otnmbrd wrote:
Also, not a bad way to go. Since money no object, use computer controls and a "joystick" for handling options .....just watch out for "nasties" sucked into impellers. Real nice, just took over a 104 foot aluminum boat (private yacht) with two 3000 hp units, joy sticks that combine to run off one stick when in cruise mode, separate for maneuvering. Bow thruster for docking. Can reverse gearboxes to flush out debris that isn't minced. Money is an object for the owners but at the level they operate it seems like it doesn't matter much. Rick |
Peter Wiley wrote in message ...
In article , Joe wrote: (Peter Wiley) wrote in message om... (Joe) wrote in message . com... Peter Wiley wrote in message ... In article , Capt. NealĘ wrote: Aluminum is relatively worthless for a boat hull. All it takes to completely destroy the hull of an aluminum hulled vessel is a handful of mercury past smeared on it. It will begin to turn to dust within hours, break apart and sink. A stainless steel boat is impervious to just about anything but strong acids. Bwahahahahahahaha. It's obvious you know SQRT(f**k-all) about metallurgy. S/steel is not a good metal to have in continuous contact with seawater. My biggest objection to aluminium is that its abrasion resistance is low compared with steel and its ultimate failure point is too close to its deformation point. Steel is a lot more ductile but does require good barrier coats to keep rust at bay. If money is no object, you build out of cupro-nickel. PDW Whats cupro-nickel? And why? I hear nickle copper is best, the copper is a perfect antifoulant. http://www.technicalmaterials.com/me...ro_nickel.html Same stuff, just you got the name wrong. Look it up in Lincoln's welding handbook and you'll find that you can weld it with MMA using ECuNi rods, good weldability. Ditto for GMA welding, GTA welding and fair welds using carbon arc tho why you'd bother is beyond me. Preheat not required, no fancy techniques needed unlike aluminium or s/steel. Good mech properties. Pretty much inert so no real corrosion probs and as you noted, naturally antifouling. Real problem is the price. Friend of mine's brother is a scrap metal dealer, got 2 tanks of Inconel one time for the price of s/steel. Wish I'd have known him back then, I woulda bought them off of him and saved the sheets for a hull. Yeah that would have been a great find. We have lots and lots of chemical and petro plants around here, If i ever feel like building a new hull. It would be nice to never have to deal with the hull again. Read about a 32 footer over in england called the Pretty Penny. Hauled it for the first time after 20 years with no noticable loss to the hull, a layer of slime and grass that was easy to simply brush off. But guess it all depends on the price per sheet. LME has copper at $3246/tonne, nickel at $14255/tonne. 70/30 cupronickel, call it $6500/tonne. A Q&D calc gives me approx 0.3 cubic metres of metal in an 11m hull of 4mm plate thickness so that'd be 0.3 * 8.9 (Cu is 8930 kg/m3, Ni 8800 kg/m3) * 6500 = $17K for the hull plate. Minimum since this makes no allowance for cost of rolling etc etc. You might be able to afford it but I can't :-) PDW Well My buddy at Farmers Copper in Galveston gave me an American version. To build a 42 footer like redclouds hull I will need approx 18 sheets of 3/16 inch and 4 sheets of 1/4 inch and one sheet of 1" for the keel board. About 13,000 pounds. With an order of this size I can have it milled to my specs. And get a super dooper discount... but it still gonna average 8.20 a pounds. So thats around 106 thousand dollars for hull deck and cabin material. Kinda steep.....but you get what you pay for in the long run IMO. Just look at some of the crap coming off the assembly lines in the 42 footer range. Pay 300K and get junk. If I ever think of upgrading I might transfer all redclouds current rigging, sails,engines ect to a spanking new hull of copper nickle. Perhaps this stepping stone theory of Bobs has some merit..... It would be nice to build a boat that you know will be around for several hundred years if kept in the proper hands. Beats the hell out of a big ass grave marker. Joe |
I heard a story about a wooden yacht the owner of which loved
so much that he put it in his will that he would give millions of dollars to some University in New Orleans, (Baylor?) on the condition they would take care of his yacht and keep it Bristol. He died in the 1970s and the university has taken him up on his offer and has his yacht stored in a special, climate controlled building and lovingly taken care of, wooden spars and all. Has anybody else heard such a tale of love for one's yacht? CN "Joe" wrote in message m... If I ever think of upgrading I might transfer all redclouds current rigging, sails,engines ect to a spanking new hull of copper nickle. Perhaps this stepping stone theory of Bobs has some merit..... It would be nice to build a boat that you know will be around for several hundred years if kept in the proper hands. Beats the hell out of a big ass grave marker. Joe |
Capt. Neal® wrote in message ...
I heard a story about a wooden yacht the owner of which loved so much that he put it in his will that he would give millions of dollars to some University in New Orleans, (Baylor?) on the condition they would take care of his yacht and keep it Bristol. He died in the 1970s and the university has taken him up on his offer and has his yacht stored in a special, climate controlled building and lovingly taken care of, wooden spars and all. Has anybody else heard such a tale of love for one's yacht? CN I can tell you a freakin nightmare stabb in the back story. Similar to yours with a FU ending. Ben Tabb, there is a hospital here in houston named after him... died a few years back. He had a lovely art deco 65 footer all teak and Mahogany, used to partol the gulf during WW11 Looking for subs. Part of his will stated the boat must be in operating good condition or be in a yard getting fixed. Nothing else. He left millions to do that. The estate people parked in in the yard here paid an outragious fee to park it, let it sit and hogg beyond repair. They ended up gutting her and crushing her and hauling her out in dumpsters. The dirty rotten sticking *******s. Joe "Joe" wrote in message m... If I ever think of upgrading I might transfer all redclouds current rigging, sails,engines ect to a spanking new hull of copper nickle. Perhaps this stepping stone theory of Bobs has some merit..... It would be nice to build a boat that you know will be around for several hundred years if kept in the proper hands. Beats the hell out of a big ass grave marker. Joe |
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