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Old 20-03-2018, 14:56   #31
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Re: Comparing RIBs to HP air floors

I used to use a Zodiac with an inflatable floor.

What a BASTARD of a thing to push along--it stuck to the water like a turd to a blanket--and eventually I replaced the floor with a honeycomb rigid floor of my own design copied roughly from the intended profile of the original floor--with some modifications at the stern and bow to improve steering and to deflect water.

It was two hundred percent better and the outboard pushed it with ease-it was just as stable as before--and so much safer to walk around on.

EXCEPT that I could no longer stuff it down one of the amas out of the way on a trip--

So--if you do not mind a heavy inflatable dangling from davits astern or cluttering up your fore deck--definitely get the RIB.

I now use a Polycraft--3 metres, if you take the foam-fileld survey option it can be certified as a life preserving device by SOLAS, costs the same or less than an inflatable of quality--I think under five grand with a registered trailer and spare wheel--and it will take a far more powerful outboard than the Zodiac did if I need to go to 15 hp, AND it rows like a dream--something inflatables never seem to do well, and it is only slightly less stable than was the Zodiac--which is about the most stable of the common inflatables...

But again--not able to be stashed under the decks in a box or bag, has to go on the fore deck or dangle from davits..

Good to fish from though--with no risk of a gaff going through one of the flotation chambers--and I have a Bimini on it--something I could not use on the inflatable Sunburn Special.

Maybe there is an American equivalent tri-hull HD polyethene foam-filled unsinkable dinghy thing available in the US? If there is--get one. And put a drop-down Bimini on it--with a chill box for beer--and it comfortably seats two and a half adults plus their kit.
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Old 20-03-2018, 16:00   #32
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Re: Comparing RIBs to HP air floors

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Originally Posted by funjohnson View Post
OP wants Hypalon not PVC... unfortunately, I haven't found a cat dinghy in hypalon.

We sold our RIB a few years ago and replaced it with a high pressure air floor WalkerBay 310 so we could store it below deck when offshore. Having sailed with the RIB on deck of our 34' Sabre across the Atlantic, I didn't want to be forced to do that again with the new boat.

The high pressure floor is incredible solid when properly inflated, but the other issues posted above are true; sand and water in the boat requires pulling the air floor out, the pvc floor does degrad with UV exposure and gasoline, and you have to be careful what you put in the dinghy isn't sharp.

I really like the air floor so far for weight, storage and cost. But, having said that.... we'll go back to a RIB if we get to the point that we are no longer doing longer offshore passages (or bigger boat)

Matt
The FAQ says it is available in Hypalon. It's not clear if that is just the tubes, or tubes and floor.
https://www.takacat.com/about-us/faq/


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Old 20-03-2018, 17:20   #33
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Re: Comparing RIBs to HP air floors

We have a 10 ft achillies with HP floor.
Both tubes and floor are Achillies version of hypalon. Inflation pressure is 3 psi and 9 psi respectively, and going a little over that gives a stiffer boat and better ride.

With a 9.8 HP 2 stroke (same size and weight as the 6 and 8 hp) it planes easily with me plus 70 kgs of kids plus gear. With two adults and two kids and snorkling gear, it is a bit of an effort to get on the plane. Made it a little painful a couple of times coming back from a few miles away after diving - 5 knots feels a lot slower than 15 plus.
With just my 10 YO boy in the bow we get up to 25+ knots on smoothish water, but it feels pretty sketchy at that speed :-)

I've rowed it a mile or so at a time with the crappy oars it comes with. Works OK, but not as good as a hard dinghy and decent oars.

The 10 YO and I can carry it up a beach between us with the outboard and fuel etc onboard.

We mostly deflate to sail, getting the dinghy from the locker, pumping it up and launching is a 15 minute one man exercise after we drop anchor. Generally just throw it over the rail to launch, use a halyard to raise on deck. Man handling the engine onboard with some support from a topping lift is a bigger hassle, but we'd have that with any dinghy. We've towed it, normally without outboard in flattish water - it throws a bigger wake than the sailboat.

If I had the space for an ali floor RIB, I'd prefer that, but the HP inflatable isn't much of a compromise really.

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Old 20-03-2018, 18:53   #34
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Re: Comparing RIBs to HP air floors

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Originally Posted by Jammer View Post
I'm still trying to work out what tenders, if any, will plane with a 6 HP motor that is correctly propped, with two people and gear.
Here is my experience with an HP Air Floor Walker Bay Odyssey 310 (62 pounds), a 2016 Yamaha 6 four-stroke (60 pounds), and two different propellers:

1 person (170 lbs). Planes effortlessly with stock propeller and has a top speed of about 16 knots.

2 adults (170, 150 lbs) plus 1 child (50 lbs) and 2 dogs (15, 8 lbs). Planes nicely at less than full throttle with stock propeller. Top speed about 12 knots. With a flat pitch prop, planing occurs sooner but top speed is reduced to about 10 knots.

3 adults (170, 160, and 150 lbs). Will NOT plane with stock propeller. Will sorta plane with a flat pitch prop and wide open throttle. Top speed about 8 knots.

After experimenting with the two propellers and various loads, my strong preference is to use the stock propeller. It has the best all around performance and also handles (steers) better.

I'll keep the flat pitch prop for towing or use on larger (slower) boats

Steve
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Old 20-03-2018, 19:19   #35
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Re: Comparing RIBs to HP air floors

I'm not one to bandwagon but this is one thing Skip Novak gets completely right.

It's all about the blowup floor. Can't beat being able to stow the dink down below. Bombard C3 badass boats
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Old 20-03-2018, 19:47   #36
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Re: Comparing RIBs to HP air floors

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Originally Posted by Panope View Post
Here is my experience with an HP Air Floor Walker Bay Odyssey 310 (62 pounds), a 2016 Yamaha 6 four-stroke (60 pounds), and two different propellers:
Thank you! That's the information I needed.
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Old 20-03-2018, 19:49   #37
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Re: Comparing RIBs to HP air floors

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So, high-pressure air floors make for a lighter boat and allow deflated stowage in a smaller space; some claim that a smaller outboard can be used due to the lighter weight.

The usual drawbacks cited (compared to an aluminum RIB) are lack of durability and lack of rigidity.

How does this work out in practice? Air the air floors good enough?
We have two Zodiac Fastroller tenders.

The first one is a 350. It has a 15HP 2T outboard on it, and it zooms around at 20+ knots with two people in, quite happily. In rougher water, the slight flex in the floor gives a softer ride, and we are very happy with it (we have had it for well over ten years now).

The second is a newer 340 (6 years now), and has a 6HP 4T (unfortunately, but it's in Europe ...). With the heavy, but low-powered fourstroke, it has no chance of planing, but still does OK, and we have used it two-up to cross reasonably rough water. Again, the slight flex in the floor cushions the ride nicely.

RIBS are nice, but you can't roll them up. For us, that's the big reason why we would not consider a RIB. When we are doing any serious sailing, we do not want the tender hanging off the davits, or lashed to the fore-deck, and at the end of the season, we can just stow below like we do with the sails (about the same size, if not smaller, than a sail-bag).

The only issue we have with Zodiac is their storage bag - do not leave in the sun, as the blue straps are not fit for purpose and turn to powder after exposure to UV for several months. We have a canvas cover made up to go over the bag, when it is lashed down in front of the dodger.
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Old 21-03-2018, 02:44   #38
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Re: Comparing RIBs to HP air floors

I have one season on my 10’ Achilles HP air floor, it replaced my old caribe 10’ RIB. I think the caribe was a couple inches longer but the Achilles definitely planes with way less effort, I had a 15 on the caribe and I now have a 9.9 on the Achilles. I’ve had a 6 on both, impossible to get the caribe to plane but not much more than 1/2 throttle on the Achilles and it planes (with two people).

The Achilles has really exceeded my expectations, time will tell how it holds up but after one season I would highly recommend for someone in your situation. The HP airfloor and inflatable keel have it perform much more like a RIB than I expected, but on long passages it is out of sight out of mind down below in a bag.
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Old 21-03-2018, 07:37   #39
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Re: Comparing RIBs to HP air floors

Hi Jammer, given the answers you provided to my questions, an inflatable should be just fine. There will be little wear from rocky or shell strewn beaches. You can mount any outboard on your pushpit and tow the dinghy if you so desire, reducing the need to inflate and deflate. You can also tow a hard or RIB dinghy but you won't have room to put it on a 25 foot boat should you need to. You can also tow a portebote and lash it to the rigging or lifeline on the side deck, although you won't want to do that very often. Good luck!
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Old 21-03-2018, 07:52   #40
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Re: Comparing RIBs to HP air floors

Quote:
Originally Posted by KD8NPB View Post
I don't think you had it inflated to the correct pressure.

Most Zodiac air floors take 11.2 psi. At that pressure, it's like a piece of plywood with almost no give. It's a small compartment of air too, so if you inflate it then put the boat in cold water, the cold water reduces the pressure substantially.

For "true tenders", I tend to prefer the Cadet Fastroller 285 Acti-V. It's one of the last "made in France" PVC tenders available in the market with a 99% welded construction of Strongan 800 material (no other manufacturer has welded floors and welded transoms). It's light, planes easily with 5/6hp, and can easily be stowed by one person. The only downside though, is I would strongly recommend investing in an electric pump such as the Bravo 12 BST HP in order to maintain the floor at the proper pressure.

I like the Fastroller 325 and 360 too, but they start getting a little heavy for me.

The Futura MK2 and MK3 with air floors are a lot of fun, but they weigh a ton. They would be more for an "expedition" boater. The heavier weight Strongan 1200 material makes them tip the scales at about 200 lb.

In my experience, CSM/CR air floors tend to be "mushy". Because they are 100% glued, their operational pressure is lower, or you risk a blowout. Zodiac's PVC floors are about 99% welded (there tends to be a few little PVC bits glued on, like the retention straps in the back), and they get overpressure tested at the factory at ~15 psi.
Everything he said.

The achilles air floors work really well but do not get quite as stiff. A coworker had a 11' achilles air floor for a slong time and was a great little boat.
Achilles also makes the LSR with a rollup aluminum floor good for storage but heavy. Also need to make sure tubes and keel are at a good pressure or the floor feels loose.
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Old 21-03-2018, 07:58   #41
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Re: Comparing RIBs to HP air floors

Also on the planing thing. It depends a lot on weight where that weight is and the prop and motor position. When I used to sell infltables for a living I in general told most people 6hp will plane 1 person and 8 to plane 2, But of course that was being a bit conservative.
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Old 21-03-2018, 13:07   #42
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Re: Comparing RIBs to HP air floors

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Also on the planing thing. It depends a lot on weight where that weight is and the prop and motor position. When I used to sell infltables for a living I in general told most people 6hp will plane 1 person and 8 to plane 2, But of course that was being a bit conservative.

So why does my Tohatsu 9.8B 2-stroke plane with one but not two with our 9’ 6” aluminium RHIB? I’ve read all these posts about people ‘easily’ planing with two people and 6 and 8 hp engines, and same for others with our engine. So what’s wrong with our setup?
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Old 21-03-2018, 13:41   #43
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Re: Comparing RIBs to HP air floors

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Originally Posted by fxykty View Post
So why does my Tohatsu 9.8B 2-stroke plane with one but not two with our 9’ 6” aluminium RHIB? I’ve read all these posts about people ‘easily’ planing with two people and 6 and 8 hp engines, and same for others with our engine. So what’s wrong with our setup?
Hard to diagnose stuff without being there. Engine not producing rated output? Prop damage -- it doesn't take much to make a big difference? Wrong prop? One easy step is to check your engine RPM at wide open throttle and compare it to spec.
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Old 21-03-2018, 13:50   #44
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Re: Comparing RIBs to HP air floors

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Originally Posted by fxykty View Post
So why does my Tohatsu 9.8B 2-stroke plane with one but not two with our 9’ 6” aluminium RHIB? I’ve read all these posts about people ‘easily’ planing with two people and 6 and 8 hp engines, and same for others with our engine. So what’s wrong with our setup?
As Jammer says - could be anything. I ran one for years on my 9 foot airdeck. Examples:
  • Load not distributed properly - may need to be forward with tiller extension.
  • Wrong prop
  • Wrong trim position
  • Very heavy people
The other thing about the 9.8hp is that it is a modified 6hp block, so the cubic capacity is quite small compared to some 10hp units that are derated 15hp. The result is low torque, which can impede a marginal load getting onto the plane.
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Old 21-03-2018, 13:58   #45
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Re: Comparing RIBs to HP air floors

Engine RPM was checked last year during an overhaul service when we got the outboard with the boat, WOT value is as it should be.

The prop is the standard 8.5 pitch and has some minor blade tip nicks. I’m going to try 7.5 and 6.5 pitch props to see what difference a different prop makes. If it is relatively low torque then a lower pitch prop may help.

Trim position is another possibility, we’ve just left it at the original setting, which makes the shaft vertical at rest.

Trim and people weight, possibly but we’ve tried various combinations and still no joy planing with two.

Thanks.
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