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Old 30 December 2006, 14:23   #1
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Deadrise - speed vs comfort

If I get the orange peril fixed and sold later in the year, I'll obviously be replacing it. The Mac range of plastic boats is the favourite option at the moment because of toughness and not needing to antifoul, but I was just looking through a "rib buying guide" thing that came with Rib Intl a couple of issues back and looking at the specs of some of the other craft, it is not as deep V hull. The Mac 570 is 18 degrees deadrise versus 25 deg on the current Destroyer, which I suppose is probably the same hull as mine? The Ribcraft 5.85 is 22 deg, the Ospreys (which is what I am most interested in) don't appear in the guide at all, which is odd as there are a load of makes that I have never heard of. One thing I really do like about the Destroyer is that it rides very well in choppy conditions and having been out in a similar size fibreglass boat yesterday afternoon, it was so noisy after the RIB, even in fairly nice conditions.

I know there are a lot more variables than purely the deadrise but is this likely to make much difference to the ride in choppy conditions? There are some video clips of the boats on a DVD that I got sent to me but only in relatively calm conditions so its hard to tell.

thanks

Stephen
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Old 30 December 2006, 16:50   #2
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Stephen, I think you might find your Humber has a variable deadrise along with the central planing pad. It's never quite a simple as we might like it to be.
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Old 30 December 2006, 17:32   #3
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Bow shape and weight has a lot to do with ride quality, particularly in the rough stuff. You will, I suspect need a deep V as well. For your environment I suspect you'll always have to comprimise on outright performance but that is all relitive, as optimum performance for a given geographical area will differ.

I like the Viper as it seems to have all the bits in the right places and dosen't seem to comprimise it's Sea Keeping qualities for outright performance. I haven't found anyone who has a bad word to say about it.
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Old 30 December 2006, 18:06   #4
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Hi Steve

You find it hard to beat the hull you've got!

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Old 30 December 2006, 20:21   #5
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Hi Steve

You find it hard to beat the hull you've got!

Jono
Jono,

I agree, the hull is great, its just the floppy bit around the outside that spoils it... by the way you have a PM.

The other thing with the Mac is that it seems to be pretty constant V all the way down the hull (about 3/4 the length) till it tapers to the bow whereas the Humber hull, as jwalker suggests, is a sort of tapered arrangement with a greater angle at the sharp end.

Would really like to try all the options back to back in the same conditions but I suspect that's not very practical! Mac do a deeper V boat which doesn't look like a RIB (don't really like it anyway) but the hull shape looks all wrong to me for performance.

Maybe if somebody gives me a free hull & tubes I won't need to buy anything
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Old 30 December 2006, 20:33   #6
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The other thing with the Mac is that it seems to be pretty constant V all the way down the hull (about 3/4 the length) till it tapers to the bow whereas the Humber hull, as jwalker suggests, is a sort of tapered arrangement with a greater angle at the sharp end.
I should have been more precise. What you described is known a warp. Variable deadrise is a V-hull with more than one angle in the V. If you look closely, or get out a sliding bevel, you'll see that the lower part of the hull up to the spray rails at your transom is a lesser angle than from the spray rail up to the tube flanges. This is not uncommon. I have also seen the angles the other way, ie. sharper at the lower section although I have no experience of a hull like that.
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Old 30 December 2006, 21:23   #7
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Stephen

If your thinking of a hard boat, have you looked at a rigid raider?

Jono
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Old 30 December 2006, 21:33   #8
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Stephen i have owned various ribs and hard boats to hoot, and every time i want to go out and the water looks a little lumpy i say it all over again. i
want my osprey back,
Ribs are what they are. a bloody hard to beat water craft,
you have been unfortunate in your purchase, but sort your tubes out you will not regret it afterwards, specially with the sea states we have to deal with,
good luck with whatever you choose,
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Old 30 December 2006, 21:39   #9
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Quote:
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Stephen

If your thinking of a hard boat, have you looked at a rigid raider?

Jono
I have, in fact I was trying to separate one from its owner before I bought the RIB but he wouldn't sell. Two months later it was up for sale for a lot less than I paid for the RIB and damn don't I wish I had waited with what's happened since but its now been sold again and its the only privately owned one here AFAIK.

The trouble is the ones available ex-MOD all seem to need a huge amount of work doing and the other problem is that they either need loads of power (twin Suz DF140s on the Defence Force one here) and that means loads of fuel and will limit my use, or with a smaller power unit they aren't that quick - and I must admit I have grown fond of the fun side of 30 knots in the last few months


On a separate question but related to the issue, has anybody got any comments about the likely performance of a 5.5m 80hp Vipermax versus a 5.8m 115hp? Jono has got an excellent deal on both and I wondered if I could save 5 grand and go for the smaller one without losing too much fun...?
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Old 30 December 2006, 22:27   #10
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Stephen

I would go for a Mariner 2 Stroke as dead simple if anything goes wrong.

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Old 30 December 2006, 22:44   #11
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I have, in fact I was trying to separate one from its owner before I bought the RIB but he wouldn't sell. Two months later it was up for sale for a lot less than I paid for the RIB and damn don't I wish I had waited with what's happened since but its now been sold again and its the only privately owned one here AFAIK.

The trouble is the ones available ex-MOD all seem to need a huge amount of work doing and the other problem is that they either need loads of power (twin Suz DF140s on the Defence Force one here) and that means loads of fuel and will limit my use, or with a smaller power unit they aren't that quick - and I must admit I have grown fond of the fun side of 30 knots in the last few months


On a separate question but related to the issue, has anybody got any comments about the likely performance of a 5.5m 80hp Vipermax versus a 5.8m 115hp? Jono has got an excellent deal on both and I wondered if I could save 5 grand and go for the smaller one without losing too much fun...?

Save the 5 grand.

Seems like you guys in the Falklands have got too much money. Have you struck oil

Er maybe thats why that little Battle group went down there 25 years ago.
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Old 30 December 2006, 23:56   #12
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Save the 5 grand.

Seems like you guys in the Falklands have got too much money. Have you struck oil

Er maybe thats why that little Battle group went down there 25 years ago.
No, but I have share options in one of the companies that will benefit if we do, and that is what might be paying for the new boat

Maybe it was, and I think the faith will be well placed within the next couple of years. Not many oil-producing parts of the world that have no terrorists but there ain't too many round these parts
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Old 31 December 2006, 19:37   #13
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Stephen

I would go for a Mariner 2 Stroke as dead simple if anything goes wrong.

Jono
Jono,

Couldn't agree more - but to change the thread slightly what's your understanding of how much longer 2 stroke will (a) be able to be sold, and (b) be able to be used in the EU/UK - various sources have told me the French and various "green" groups are trying to get the ban made retrospective so all 2 strokes are outlawed....

Simon
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Old 31 December 2006, 20:10   #14
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how much longer 2 stroke will (a) be able to be sold
Old Tecnology 2 strokes stop being sold in the uk somtime 2007, and stop being made in a couple of years as military/commercial users need time to adjust.

Optimax & Etec will obviously continue.

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Jono,

how much longer 2 stroke will (b) be able to be used in the EU/UK - various sources have told me the French and various "green" groups are trying to get the ban made retrospective so all 2 strokes are outlawed....
What a load of cobblers, how would they ever police it !

I think this as been covered time & time again on various threads, so im not gonna go on about here.

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Old 31 December 2006, 20:29   #15
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Thanks Jono, reassuring news.

Think the confusion arose as some inland waterways were looking at banning all 2-stroke : this would be quite easy to police as a licencing system exists.

Think they may be dropping the idea pretty quickly in the light of planned budget cuts for BW though...
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Old 31 December 2006, 20:34   #16
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Think the confusion arose as some inland waterways were looking at banning all 2-stroke : this would be quite easy to police as a licencing system exists.
Totally agree

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Old 01 January 2007, 17:58   #17
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On a separate question but related to the issue, has anybody got any comments about the likely performance of a 5.5m 80hp Vipermax versus a 5.8m 115hp? Jono has got an excellent deal on both and I wondered if I could save 5 grand and go for the smaller one without losing too much fun...?
Stephen, size does matter If you have the necessary go for the bigger one. Believe me, I have been there. If the seas are as bad down there as I have read from yourself somewhere, and you get caught out in it, you will not regret that extra outlay!
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Old 01 January 2007, 18:36   #18
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(b) be able to be used in the EU/UK - various sources have told me the French and various "green" groups are trying to get the ban made retrospective so all 2 strokes are outlawed....
Simon
Various places in California tried this (succeeded, to a degree), but the ban had to be done based on emissions output, rather than mechanical type.

This resulted in a couple of lakes (Tahoe and, what, Almanor?) banning any motor that did not meet CARB (Calif Air Resources Board) 2001 emissions specifications, or the Federal EPA (US Environmental Protection Agency) 2006 specs. In effect, this bans any non-Direct Injection 2-stroke motor. Currently, all 4-strokes, diesels, and Direct Injection 2-strokes (Ficht, Optimax and E-Tec's are prime examples) are still legal to run on these lakes (actually, if a non-DI 2-stroke met the CARB or EPA specs and were certified as such, which none of them are, they'd be allowed to run also.)

There has been talk of an outright ban on 2-strokes, but I can't see it happening given the newer cleaner burning technologies. Of course, I've been wrong before, so who knows.

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Old 01 January 2007, 18:44   #19
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Stephen, size does matter If you have the necessary go for the bigger one. Believe me, I have been there. If the seas are as bad down there as I have read from yourself somewhere, and you get caught out in it, you will not regret that extra outlay!
Thanks, 1 vote for the bigger one then. The thing is, 5 grand is a lot of money (a third more) for basically a foot more boat (ok and a bigger engine!), and I wouldn't have thought that it made much difference. I can see that a metre increase would make a noticeable difference in terms of bridging wave crests at speed etc. - but only a little ickle 30cm?

Anyway it now looks like nigh on 3 months before I get this thing fixed properly so not exactly a big hurry to make a decision...

Has anybody been on or been with 5.5m boats alongside 5.8 in the same conditions on the same day and noticed much difference? For me it is the difference between being able to afford it without massive hardship and being quite a stretch to find the cash for the more expensive one - though that is the one I would like!
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Old 01 January 2007, 19:16   #20
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What about some sort of compromise - go for the larger boat, but cut back on some of the add-ons. Less seating, for example, or ditch the A frame.
Perhaps the electronics package could be trimmed back and do you need a brand new trailer?.......
As and when funds allow, these items can always be added later, but you'll struggle to add another foot to the length of the hull
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