aluminium project - Page 2

codprawn · 26 January 2007, 03:31

Quote:

Originally Posted by pop

have you used both then coders? i have not seen many ribs with Rolls Royce jets. hamilton seem well used in NZ's commercial relm, i have to say i am not an expert on jets so all comments are taken into consideration.

madmat do you run on surface drives?

Jhon i am right in thinking the yellow fin never got off the ground, am i not?

thanks

In fact more and more RIBs etc will use them - the new Offshore Raiding Craft for the UK use 2 jets to give 36kts fully loaded.

http://www.rolls-royce.com/marine/ma...fast_craft.jsp

Have a look at the slides on the page - it shows a US RIB that does 50kts with RR jets. Can't save the piccies out though - looks awesome!!!

Some of the latest advanced warships use KaMeWa/RR jets - the new stealth designs in particular.

They tend to concentrate on the bigger units but they also do them for smaller craft. Hamiltons go up to about 3000kw - the Rolls Royce units go up to 36,000kw!!!

pop · 26 January 2007, 05:07

Yer they do look nice and that rib seems to go well 50kts, but how much faster than 50 can you get from a jet? speed was not important in the beginning but its becoming more and more appealing. the hard part is to combine both good sea worthiness with the option to do over, or 60kts when the conditions will allow.

i know that jet skis and smaller jet boats get over 50 so why do hamilton say that its hard to get over 50?

do you know a ruff price on the RR jets?

John Kennett · 26 January 2007, 09:37

Quote:

Originally Posted by pop

hamilton seem well used in NZ's commercial relm, i have to say i am not an expert on jets so all comments are taken into consideration.

My guess is that you'll end up using Hamilton Jets. They seem to be pretty much the industry standard in NZ , and you've got easy access to a lot of local expertise. If you go that route you've got a good chance of getting it right first time, but if you go for a less common surface drive you'll basically be building a prototype.

Quote:

Jhon i am right in thinking the yellow fin never got off the ground, am i not?

They're not on the market yet, but I fully expect to see them for sale in the next year or so.

What are you going to use the boat for? Is it just for fun, or for racing?

If, on the other hand, it's for commercial passenger carrying does it actually need to be that fast? For thrill rides 30-40 knots is usually plenty as the perceived speed is so much higher. You may even have trouble insuring for passenger carrying at higher speeds.

Just a thought . . .

John

Matt · 26 January 2007, 11:38

Adam's designing the boat - let him guide on choice of drive as well.

Considering the hull design seperately from the drive package would be a mistake. Depending on the weight, power, stepped, unstepped etc etc will guide the suitability of any given drive.

e.g. If it's an unstepped hull looking to go 50 knots, IMVHO a surface drive would be a difficult choice since they provide little bow lift.

Conversely a jet on a stepped hull might also be a bad choice since the water going into the jet may well be highly aerated losing efficiency
etc etc

What about a pair of the new 350ish hp yammie V8 outboards.
Best of both worlds.

pop · 26 January 2007, 20:47

John, the first rib is for me and yes i would like it to be able to do around the 60kt mark. i will be using it to get out in the wilderness and extended cruising. the second rib will be for passanger carrying, the current boat runs at around 50. the only speed restriction set in nz is by the insurance you are right and they will not insure unless you stay under 70kts

i was happily suprised. i would like to think the passager one will reach 55-60.

madmat
your comment "why dont you let adam decide the drive unit" ofcourse adam will have a huge part to play with the spec of the rib however if you are spending the money and time that i am on the rib its quite nice to talk with friends about what possible drives i can use to propel the rib, plus if i want to be told how my rib looked, worked etc i would not be using adam on the other side of the world i would just get another scorpion. the outboard option is just out of the question on my rib but i could get interested in the passenger rib haveng outboards.

got any pics of your rib? what engines do you run?

codprawn · 26 January 2007, 21:00

I think the only sensible way to get that speed is to use outboards - have a look at the big Ring and Revenger boats.

pop · 26 January 2007, 21:21

I can see your point coders but i cant get petrol where i live only diesel, there has to be away around this and buying a tanker is not it.

codprawn · 26 January 2007, 21:41

Shafts with V drives? Engines at the back and shafts run underneath them.

codprawn · 26 January 2007, 21:56

Here is a good link for the US RIB running waterjets capable of 50kts

http://www.specwarnet.net/vehicles/NSW11mRIB.htm

I think surface drives must be the way to go for very high speeds though - have a look at the Sunseeker XS2000 - uses Trimax surface drives with 2 speed gearboxes - already proven so not so much messing about!!!

John Kennett · 26 January 2007, 22:06

Quote:

Originally Posted by codprawn

have a look at the Sunseeker XS2000 - uses Trimax surface drives with 2 speed gearboxes - already proven so not so much messing about!!!

. . . and it's a great feeling when the gearbox is flicked into second. Lots of grin value!

If you want to talk high perfromance stuff have a look at www.boatmad.com - when they've stopped taking the piss out of you for building a RIB not a speedboat you'll probably find some useful info.

John

Matt · 26 January 2007, 22:15

Actually, that's not what I said. I said to be "guided", not "decide" because the wrong choice would be a disaster. IMVHO, The performance you want is going to be quite expensive in jets simply because they will suck soo much power at the performance range you're looking at, so you'll need BIG motors and BIG jets.

Plus, if you fit surface drives, surely they'll still suffer from weed etc as much as outdrives? But then if you're looking as 60+ knots, I reckon you're in the 800+hp range anyway which I suspect would be more than you want to put through outdrives on diesel. So it seems to come back to, if you "need" to go that fast, on a bot that size, surface drives are your most logical choice. It's a shame arneson are so expensive, but you do get what you pay for. Have you been in touch with them - I'm trying to remember the name of the guy to speak to - Rick Wimp rings a bell.

Quote:

Originally Posted by pop

madmat
your comment "why dont you let adam decide the drive unit" ofcourse adam will have a huge part to play with the spec of the rib however if you are spending the money and time that i am on the rib its quite nice to talk with friends about what possible drives i can use to propel the rib, plus if i want to be told how my rib looked, worked etc i would not be using adam on the other side of the world i would just get another scorpion. the outboard option is just out of the question on my rib but i could get interested in the passenger rib haveng outboards.

got any pics of your rib? what engines do you run?

Matt · 26 January 2007, 22:19

Never seen one on a boat, but have seen them on a demo rig - looked pretty flimsy to be honest. Codders just came up with the other name I was trying to remember - trimax. Fabio Buzzi knows a thing or 2 about putting monster diesel power through surface drives.

Quote:

Originally Posted by pop

Hi people

does anyone know of these guys (http://www.pulsedrive.net/index.htm)? they have fitted a scorpion out and few other ribs.

slimtim · 26 January 2007, 22:22

hi pop,

i'll be keeping an eye on this thread, looks interesting. Cheers for helping out Thom a few weeks back, he said you're a top chap

Tim

pop · 27 January 2007, 01:58

hi guys

John thanks ill have a look through the threads thanks.

codprawn: i have looked at trimax,they look very simple which i like

. the sea rex looks like the one, i will send them an email asking cost ect. i will post my finding here. thanks

mad mat: sorry i thought i read "decide" its the good old dyslexia( did i spell it right?) coming back into play. you are right i will let adam guide me to a certain degree however i like to cost things up and get it clear in my mind exactly what i want then i can move onto the next stage. on the point of maintance no sterndrives are no way near the same problem, my friend/competition (b$st!rd) runs the http://www.excitor.co.nz/ and the maintance on the surface drives are minimal, the drive he runs are SF30 Seafury Surface Drives they seem to keep up well considering they are run each day, he pushes out 1,600hp.

slimtim: it was nice to have an english sense of humour, tom is a nice bloke, has he sorted a job back in the uk? if not tell him to get in touch i can have an ask around from over here. the NZ season is in full bore now so he could get sailing right away. i wish him good luk in the future. how is the island mate? i miss my mates back there and going for a surf on compton

Cookee · 28 January 2007, 12:49

Pop - see my answer on Boatmad!

codprawn · 28 January 2007, 19:05

Quote:

Originally Posted by Cookee

Pop - see my answer on Boatmad!

Funnily enough almost exactly what I said a little earlier.

John Kennett · 28 January 2007, 20:32

Quote:

Originally Posted by pop

I can’t have stern drives as the sea creatures get in, on and around creating a major maintenance problem for me.

Just looking back at your original post . . .

Won't you have similar issues with surface drives?

John

pop · 28 January 2007, 22:25

Hi ribsters for the people who dont read boat mad,

sent an email to all drive manufacturers, I hope they get back to me with a price and on guarantees with their product. I'll let you know. The other option I could go for is what coders mentioned, the outboards, but my problem is that I don't have a petrol station, does anybody know where I can buy a big petrol storage tank on wheels? (i bet its cheeper then the surface drives) Then I have the opportunity of having outboards, which would be good from a maintenance point of view. Does anypone know how much fuel an F250 yamaha goes through?

codprawn · 29 January 2007, 01:52

Depends on the laws in NZ. I have a 400L diesel tank off a lorry in a trailer as a fuel bowser - you can also buy towed bowsers cheap enough but often it's the laws that stop you.

A 250hp outboard can use as much as 80L an hour at full bore - half that cruising.

The sort of money you have been talking you could use the military spec Evinrude ETEC outboards that will run on diesel or kerosene as well as petrol.

seafariskye · 29 January 2007, 22:13

I have a searider surface drive on my aluminium boat, it weighs 7 tonne with 14 on board, does just under 40 knots, coupled to 460hp inboard - is a remarkable bit of machinery, and has been great - simple shaft drive basically, through gearbox, and out.
To say
Originally Posted by codprawn
Surface drives are great for long fast runs in calmish waters

Is in my mind complete bollocks, and comes for an old wifies tale. there are different ones about, but choose the one that will suit you?

Waterjets - i also have a procharter with one of these in, goes great, manouverabiliy is second to none, and have no problems apart from it does the complete opposite in reverse, than what you are used to - 390hp cruises at 24 knots, flat out 32 knots (ish) but i do agree they need allot of power, but have come on leaps and bounds in the last 6 years even...
Again back to the old wifies tale that anything with a waterjet on looks like this....

The pulsedrive carry on, have been attempted to get in touch with them - heard nothing, and will not attempt again, there are just as many moving bits in the thing as a watch, and would make a good guess at the majority of them going bang, in a very short space of time.

Pete