Dive Boat/RIB

[paintsnow]

hum, ive been diving off of a rib and we had 20 sometimes more people on it and it was okay. everybody sat in the tubes and the tanks were in the middle.

pontoons are too slow, big, heavy and would be much harder to store int he garage.

heres the exact boat ive been diving off of
GOMMORIZZO - Modello 7.50

its 24.6 ft, so if that for 20 people each one gets 1.23 ft of tube
a 17.5 ft boat for 10 is 1.75 ft of tube each.

if you look at the center picture it shows the boat from above and the tank rack, and the bottom left shows it full of divers with room to spare.

the way it worked was everyone set up a tank before boarding and then that and the 2nd tank went into the rack and got bungied down. weights under feet and fins in the fin box with mask in one of the foot pockets.

sure there wasnt room to dance but it was perfect and comfortable for longer rides then the lakes would really allow.

also a pontoon on a river would be like taking a mobile home to the drag races i would think.

 

[GrumpyOldGuy]

20 divers in a 25 foot boat is crazy. One diver with gear is at least equal to 2 passengers (USCG allows about 140 lbs per person for calculating load). A diver with gear and a spare tank is something around 300lbs.

Also, thinking that you can calculate divers per foot of boat is bad math. The load is somewhat proportional to length x beam. So the longer the boat is, the load expands exponentially, not in a linear manner. A 17.5 foot boat of any type is small and suitable for 3 or 4 divers.

 

[paintsnow]

then how do they come up with the 11 person rating?

 

[GrumpyOldGuy]

They take the maximum safe load which in part is based on the displacement and divide by 140 lbs for USCG. This is a simplified explanation, it gets more complex than that and I don't know all the details. It works for average 140lb passengers, not really a good number IMO for normal US passengers, really bad for average divers and all there gear.

 

[Nemrod]

People don't buy rubber boats in the USnA. There is a huge bias against them, even RIBs.it is changing slowly. They tend to be more expensive or at least as expensive as premium hard hulls and they have no resale value in North America.

I don't understand and must have missed the part about 20 divers. If this is a commercial operation then you will need a captain's license, a ships license and a variety of things including insurance which I bet will but a damper on the 20 divers. The rated capacity is a somewhat artificial number, it is not intended to be a practical measure of persons. This is a pic from a couple of years ago when I pulled the Cancuro out and reworked the floorboards and then gave up in sticker shock over a new engine and bought a Boston Whaler instead--lol. I have used 15 to 50 horse engines on it and despite the naysayers, I have dived six from it. It is a crowd, you sit on the tubes, pile the gear in the middle. Not a two tank dive however, we were fitted out for a single dive. It would quickly become a miserable adventure with that many people. My wife and I have had it out 20 miles or more. Yes, we had a radio, depth, loran initially and last time a gps. Today I would have a PLB and some other items. I can tell you, by the time you get anchors and other equipment onboard your not going to want 20 divers on a 20 foot boat. This one is 14ish (4.2 meters), all hypalon and neoprene, rigid fabric bottom, wood keel, made in Italy by Novurania, circa 1984.

Anyways, good luck and hope it works out for you whatever it is that your doing.

N

 

[captain]

They take the maximum safe load which in part is based on the displacement and divide by 140 lbs for USCG. This is a simplified explanation, it gets more complex than that and I don't know all the details. It works for average 140lb passengers, not really a good number IMO for normal US passengers, really bad for average divers and all there gear.

In the aftermath of the sinking of a tour boat on a lake in the northeast the Coast Guard either has or is considering raising the passenger weight used to calculate capacity to 160 pounds, still low in my opinion.

 

[friscuba]

Yup, if you're looking commercial you'll have a bunch of hoops to jump through - no foreign made hulls, boat inspected in the building process, licensed Captains, etc. I know of a couple 25 foot Ribs locally that are rated for something like 12 divers or 18 snorkelers, I think the price was about 135K turnkey + shipping.

 

[Toyon]

If you're looking for the cheapest possible boat for 10 divers, and you'll be using it on flat water, rent a houseboat. It will accomodate your dive team, you can walk away from it, you won't have to store it or maintain it, and it will be there when you need it. Plus you can barbecue steaks on it and pull frosties out of the fridge.

RIB's are well-suited for swells and chop, but they are quite heavy compared to soft-floored inflatables, so you are really limited to trailer/ramp launching them...is that an issue for you? They are also quite expensive. By contrast, a soft-floored inflatable of 13 to 15 feet length can be carried easily by two people and unrolled and launched from almost anywhere, above or below water. You aren't planning to launch from underwater, are you? If you are, you might be interested in a government job I've heard of, called, "Navy SEAL."

There's no denying the sex appeal of a thirty foot RIB with massive outboards, or the impressive distances they can cover pronto. You can spend six (or nearly) figures for a new one, and you would need at least a thirty footer for ten divers, and they are still going to be on top of each other:

Inflatables at Defender.com

Protector NZ

Someone remarked in this thread that a friend had bought a gov't surplus USCG RIB, but for the same dollars, where you'll be diving, you could charter a boat many times, and your locations do have boats available for charter.

I say this as the owner of a 46 foot powerboat, an 11 foot Avon RIB, a 17 foot Thistle (Welcome to Thistle Class Association) and an 8 foot Achilles inflatable. You can just barely get two divers into the Avon; with a 15 hp outboard, it's on the edge of being able to plane. Really you'd want a 25 h.p. outboard and a 13 foot RIB to be doing some serious evolutions. With a 13 foot non-RIB Avon Sportboat we used to have, I could just barely get three divers into the boat and the 25 h.p. outboard would still get the thing planing. On one occasion, I pulled the whole thing out of the back of the station wagon and had it assembled and launched within twenty minutes from a wharf in LA Harbor, carrying the thing down a gangplank to a narrow floating dock. Couldn't have done that with a RIB.

Bottom line is that when it's possible to do so, it's cheaper to charter, even if it seems expensive. But if you have your heart set on a boat, buy the right one for the job; don't expect the boat to perform beyond its limits.

Here's a great place to find RIBs:

Yachtworld RIBs

Same site, broader search on "inflatable"

Yachtworld and eBay are good places to search, and Boston Whaler's lifetime guarantee is pretty amazing. Because they are entirely rigid, they are unforgiving alongside other boats, but, as far as boats go, they are low maintenance boats.

 

[Toyon]

Nemrod, what a beautiful job you did on those floorboards.

 

[Nemrod]

Thank you Toyon, while the boat is 22 years old it was only used routinely for the first 8/10 years and then it sat (stored) as I pursued other intersts. In more recent times I have taken more interest in my kayak and now of course our Boston Whaler. I stripped the marine ply floor to bare wood and refinished with a two part polyurethane aviation grade varnish system I had left over. Fortunately the floor was not really that bad, I had installed heavy velcro hooks around each section perimeter and then cut and had sewn neoprene backed outdoor carpet covers which greatly reduced the damage to the floor. The boat is in great shape, it has a few minor issues but nothing that prevents going to sea short of I need a new engine--lol. When I mention that to my wife gives me this look, you know, I don't think she was ever terribly fond of that rubber boat, the Boston Whaler is more her speed. This is her about 1984. I think we had motored up the Suwanee to Ginnie and anchored out in the run. You might not be able to do that anymore??

N