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Old 19-09-2014, 11:44   #16
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Re: RIB sizing for family of 4 plus med/large dog?

My assumption on RIB vs roll-up floor is number of passengers plus dog with sharp (though trimmed) nails and the ability to beach in surf on sand or gravel beaches.

If I were sans dog and mostly looking to go from boat to dinghy dock I'd for sure consider inflatable floor as a much lighter alternative.
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Old 19-09-2014, 11:47   #17
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Re: RIB sizing for family of 4 plus med/large dog?

Quote:
Originally Posted by Wind River View Post
I can't speak for what you need but this is what I have and what it will and will not do.
I have a 2009 West Marine RIB350 (11.5 ft.) with a 25hp Mercury 4 stroke outboard (also 2009). It carries two adults, a 70 lb. dog and misc gear and groceries and will plane and move along fine, probably faster than I really should be going. Put four adults in it and no matter where you put them in the boat, it will not get up on a plane. That was very disappointing to me as I was hoping to get 3 adults and dive gear up on a plane to get out to the dive site in a hurry.
I have not tried changing props or anything else to improve the situation but my guess is that is why I found this virtually new dinghy and trailer for sale. I was told the previous owner was 350 lbs+. Probably didn't move him as well as he hoped either.
You have something wrong. a 25hp ought to be a rocket even with 4 adults aboard. My 10 ft Caribe with 2stroke Yamaha 15 would plane with 4. None of us were big though.
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Old 19-09-2014, 15:24   #18
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Re: RIB sizing for family of 4 plus med/large dog?

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Originally Posted by Cheechako View Post
You have something wrong. a 25hp ought to be a rocket even with 4 adults aboard. My 10 ft Caribe with 2stroke Yamaha 15 would plane with 4. None of us were big though.
+1

My 340 Avon rib with 25 horsepower will plane with five aboard. It will achieve about 30 knots with up to two aboard. Of course, none of us is very fat -- YMMV.

But I think something is wrong -- wrong prop maybe?
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Old 19-09-2014, 15:30   #19
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Re: RIB sizing for family of 4 plus med/large dog?

To the OP:

You’ve run up against one of the fundamental design problems of cruising sailboats, a problem which severely impacts boats even much bigger than the one you are contemplating. See for example the thread on the “Ideal 60 – 65’ Cruising Boat” which has been active recently.

Your design specification is not realizable on a boat the size of a Pearson 365, or even one much bigger. You will have to make a painful compromises here or there or in several places.

I have a lot of miles in a Pearson 365, as it so happens, and the dinghy solution was this: Garhauer davits and separate stowage of the 5hp engine on the rail. AB 9’ soft floor dinghy. Roll up the dinghy on passage. The painful compromises here? Let me count the ways:
1. A 9’ soft floor dinghy won’t carry four people and a dog, and won’t plane. It’s just a little tub to ferry two, maximum 3 people to a very nearby landing.
2. The davits look awful, add length, add windage which noticeably hurts sailing performance, and create a structure good for bashing into piles as you push off a berth. On the plus side, at least you get a place to put your solar panels (whoopee).
3. Getting the dinghy up and down is a pretty laborious process – you have to take the motor off and crane it up (or down) separately, put it together, etc.
4. Deflating and rolling it up for passages is a real PITA. And then you have to stow the rolled up dinghy

This is probably the best possible dinghy solution for a boat this size, but one has to admit that it is basically a crap solution.
As boats get bigger, this problem does allow solutions with progressively fewer painful compromises. But they don’t disappear until a boat is well into superyacht territory.
My present boat is 54’ on deck, 16’ beam, and two and a half times the displacement of a P365. That ought to give me some wiggle room, no? But my dinghy solution is still unsatisfactory. I have a 3.4 meter (11’) Avon rib with center console and wheel steering, and a 25 horsepower outboard. So far so good – this is now finally a dinghy which fulfills something like your design specification – you can carry four or even five people in it, and it will plane even with 5 on board, if the people aren’t too porky. With wheel steering, it’s comfortable to drive for longer distances, and so you can really get out and go places and explore on this dinghy. It’s not big enough to be actually seaworthy, but I have crossed the Solent four times in it (which goes fast at 30 knots), and you can even pull a waterskier. Since my boat lives on a mid-river mooring with no walk-on access, the dinghy is extremely important – it really is my family car, almost literally. I have to get in the dink every time I walk on shore for anything, and I use the dink to buy groceries and all kinds of other things.
OK, but that’s about all the good. Here is the bad:
1. Such a dinghy weights 150kg or probably more, and requires massive powered davits to lift conveniently.
2. These massive powered davits are hideously ugly and completely ruin the beautiful lines of the boat.
3. These massive powered davits add 6 feet to my boat’s LOA, complicating berthing and making Med mooring impossible.
4. The davits plus dinghy create massive windage.
5. 150kg of dinghy plus the davits and hardware add a considerable amount of weight far out at the end of the boat, with corresponding effect on trim and polar moment of inertia – negative effects of course.
6. The davits are horrendously unreliable and require constant repair. . By far the all-time star of my to-fix list. Now the lifting mechanisms have been out of commission since the spring with parts impossible to source, and I have to use a block and tackle instead. Oh, joy.
7. You cannot store a dinghy of that size on deck of even a big boat like mine. So you are

Did you guess by now that I hate my davits?

So on a boat the size of a P365, you will need to start out with the proposition that you are essentially screwed however you figure it. In my opinion, there are two kind of major ways to go:

1. Do like my example above and fit the davits and live with the disadvantages of them. Try to choose the best possible dinghy which will fit them. Maybe an air floor dinghy will work better than the soft floor kind I used to use. Maybe you could squeak in a little bigger one – maybe 10’? But remember that the bigger it is, the bigger the other headaches – it’s a no-win situation.

2. Or skip the davits, and save the windage, LOA, and other issues. In this case, you will have to commit to inflating/deflating, rolling up/unrolling the dink very often, craning it on and off the deck, and so in this case you really won’t want anything bigger than 9’. You will compromise severely on convenience and functionality of the dinghy, but at least you won’t screw up your boat.


There are other solutions -- PortABotes, which fold up and can be lashed to stanchions. Just to name one example. Hard dinghys. Towing. But inflatables are the choice of 97% of cruisers for very good reasons -- they are much more stable, don't scratch your topsides, and some of them can be rolled up.

There is no "recipe for happiness", in my opinion. Just various more or less painful compromises. I can't even solve it on my 54' boat. One of the best solutions I've seen is on the 64' Halberg-Rassey -- which has a kind of "hangar deck" behind the transom, which swallows a small RIB whole and serves as a kind of uber-lazarette. Other than occupying an awful lot of hull volume, that doesn't really have any disdvantages. But that doesn't really work on a boat less than about that size. So the rest of us can dream on. . . .
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Old 19-09-2014, 15:36   #20
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Re: RIB sizing for family of 4 plus med/large dog?

P.S. -- there is just one other solution to the dinghy problem --

Buy a catamaran.

A cat doesn't really mind davits, because of the great width between the hulls.

The davits don't ruin the beautiful lines of a cat, because cats have no beautiful lines -- they can't possibly be made more ugly than they already are when they're first launched

Joking aside, catamarans, even ones of modest size, do really deal vastly better with the dinghy problem than monos, even large ones, do. Worth thinking about.
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Old 19-09-2014, 16:02   #21
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Re: RIB sizing for family of 4 plus med/large dog?

I wonder whether anyone here on this thread has had the experience of dripped outboard fuel onto their airfloor. We were warned that the gas ruins them pretty fast, and that it is hard to keep from spilling some. Also, that the outboard oil was hard on them. Is this true? or an old wives' tale?

Ann
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Old 19-09-2014, 19:28   #22
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Re: RIB sizing for family of 4 plus med/large dog?

Whitebread,
For your application, you're going to want a RIB a bit larger than most....(although my application is similar, so I'm actually recommending a RIB/engine combo like I have....and no, this is not just someone saying "mine is best" / "do what I do"....)

A Hypalon tube (18" dia tubes preferred) ~ 12' RIB...good for 2 - 3 adults with full SCUBA gear (one of my requirements), and/or 2 - 4 adults w/ basic cruising supplies (another of my requirements), and/or plenty of room for provisions, etc.

Until you've had to make a few mile run thru some chop / surf, etc. back to your boat, with the sky darkening, with your family, gear, etc., you may not appreciate the little difference between 11' RIB w/ 17" tubes...and a 12' RIB w/ 18" tubes...
{FYI, I started with inflatable back in the 1970's in Caribbean and the Med, etc....and I'd never go back to a soft floor, soft bottom dinghy...}

With the requirements you outline and a budget of $5k - $7k, you're going to be looking at either a 12' Caribe C12 or a 12' AB 12 VS RIB, with a 15 hp 2-stoke Yamaha, or maybe a 20 - 25hp Yamaha 2-stroke....(possibly a 18-hp/20-hp 2-stroke...tohatsu / nissan, susuki, etc.)
Although, if you're buying in the US, you may end up with a 4-stroke....if so, get the 20-hp Yamaha (same weight as the 15-hp 4-stroke)....


But, to be sure, Ann has summed things up very well here!!! (inflated or deflated...)
Quote:
Originally Posted by Ann T. Cate View Post
This one is going to come down to how big a RIB you can actually stow disinflated on your foredeck. Make any possible deals contingent upon it's fitting there. (Dealers usually do not know this dimension, so trial fit is the way to go.

I'd recommend a 3.4 m. dinghy, if it will fit. With a 15 hp 2 stroke, and possibly a special prop (keep the one that comes with the motor for a spare.
Have a look here....






EDIT:::
I just saw page 2 and Dockhead's postings....and he makes some good points....but...
But, for gunkholing thru the Bahamas with a big family and dog...and then heading down island is a specific application that is well suited to an RIB....
(whether you end up with a boat big enough for a 12' RIB or not....that's something none of us can answer for you, as you don't have the boat yet...)
Just remember that TOWING your RIB (w/o engine) is done EVERY day by 100's of cruisers thru the Bahamas....and securing it on the foredeck when heading offshore on a passage is always a good idea....(but I have seen many successfully towing offshore....not my recommendation, but some do it anyway...)





Here are some specifics....including dinghy towing options in the real world (yes, it IS done safely all the time...)
Quote:
Originally Posted by Whitebread117 View Post
What size RIB/motor would be preferable for a family of 4 plus a 55lb dog?
Either a 12' Caribe or 12' AB dinghy (both having 18" tubes), with a 15 hp 2-stroke Yamaha, or maybe even a 20 - 25hp Yamaha 2-stroke....(possibly a 18-hp/20-hp 2-stroke...susuki, tohatsu, etc.)
Although, if you're buying in the US, you may end up with a 4-stroke....if so, get the 20-hp Yamaha....
We're starting out poking around the Bahamas, then headed south and eventually way west as the kids get a bit older.



Need a RIB for frequent use exploring and ferrying family (plus supplies or dog- not likely both at once) to/from boat anchored out....
Although the smaller alum-hulled AB's are light and fast....for long-term, no-maintenance, no-fuss reliable service, I'd go with a fiberglass hulled RIB....
Probably 12' long...and probably one with a bow compartment for stowing your dinghy anchor/chain/rode, fresh water, a gallon of extra gas, 2-cycle oil, engine lock and cable, towel, etc. etc....





We're starting out poking around the Bahamas, then headed south and eventually way west as the kids get a bit older....
......RIB needs to fit on davits for day to day, but fit on foredeck for passages.
For gunkholing thru the Bahamas, towing an RIB (w/o engine) is not only acceptable, but if done with a double tow line / bridle (especially one made from Dacron-over-polypro, floating towline) is an easy, effective, and almost trouble-free approach, so you may be able to save some $$$ on davits...
And, except for Nassau, there's no need to worry about dinghy / engine theft in the Bahamas....(now, once you head further down island, and find yourself in higher crime areas...you will need to haul the dinghy out of the water every night....another reason to love the Bahamas!!!)





I don't want any excess bells and whistles, but I want a tough dingy and would rather pay a bit more once than go cheap and settle for aggravation over time. That being said I'm assuming I'm looking at AL floor and Hypalon tubes. $5-7k is the reasonable max budget for RIB plus motor...
...Planing ability preferable but not absolutely required.
A Hypalon tube (18" dia tubes preferred) RIB...
either a 12' Caribe C12....or a AB 12VS....
w/ 15-hp - 20-hp 2-stroke....and add some "fins" (cavitation plate "fins") for easier / quicker planning...

Fiberglass hull / floor....if you look at the weights of the various RIB's, the alum hulled ones are NOT really much lighter....for the average 11' - 12' length, same tube diameter, same features (with or without bow storage compartment, with single hull or double-hull, etc.)...you find the alum-hulled models to be only about 5 - 10 lbs lighter....
(yes, for the smaller 8' - 10' lengths, with smaller tubes, the alum hulled RIB's are quite light....for your application, you're going to want a bigger RIB...so, alum won't save you much weight....and the lack of maintenance issues / paint peeling / etc. of fiberglass hulls, makes it a better choice for most...)




Going just by weight capacities it looks like 10' or so but looking for advice from those with first hand experience.
10' is going to be a tight fit for your family and your application....but it is doable....
Although my recommendation for 12' above, still stands....




Thinking motor would need to be at least 15hp to have any chance of planing but don't want to go over 20hp or I'll be the only one who can load/unload the thing. 2 stroke vs 4 stroke I don't really care, with a very slight bias towards 4 stroke.
No matter what engine you get, you'll want an engine hoist / lifting davit....my recommendation is: Garhauer LD-1....
Hands down Garhauer is not only one of the greatest / friendliest marine businesses ever, they make truly fantastic gear!!!

And, if buying in the US, you'll be buying a 4-stroke....so buy the "hp" that does the job for you, but doesn't add any additional weight (such as the Yamaha 4-stroke 20-hp being the same weight as the 15-hp)....


I hope this helps...

John
s/v Annie Laurie
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Old 19-09-2014, 19:53   #23
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Re: RIB sizing for family of 4 plus med/large dog?

Dockhead -

All very good points.

Regarding cats, if they'd only become popular 20 years or so earlier so the used market would be reasonable they would be on my short list. However the only ones I've found in my price range (minus the backyard built Pivers, Wharrams, etc) are some Gemini 3400s that were fairly rough. In the current market a dollar goes exponentially farther on a monohull and we're 100% committed to the go young(ish)/go now mentality, so we're really only able to consider monos.


ka4wja - thanks, that's great info. Boat choice will come down to what's in the bank by the end of next year at latest. I'm self employed (industrial automation contractor) so annual income varies greatly depending on what contracts I pick up. The upside is the income can be dramatically higher than a similar full-time position, the downside is budgeting is difficult due to the peaks/valleys in workload. So essentially we're saving every dime and by the end of 2015 (absolute latest) we'll have enough to take off for several years. My workload between now and then will dictate whether we're buying a plastic-fantastic from the 60s/70s at the end of the year and dealing with less space, or whether we're picking up a slightly more modern design with more room for "stuff" and heading out next summer. We live very frugally already, so monthly living expenses won't likely vary much either way.

Overall great thread with a lot of valuable info. Thanks to all.
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Old 19-09-2014, 22:10   #24
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Re: RIB sizing for family of 4 plus med/large dog?

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Originally Posted by Cheechako View Post
You have something wrong. a 25hp ought to be a rocket even with 4 adults aboard. My 10 ft Caribe with 2stroke Yamaha 15 would plane with 4. None of us were big though.
Yeah someting wong wiff your 15hp iffin' yo naht getting speed. My 15 hp and 11 ft flys. Scares the bejesus outta everyone. No prob 4 peoples. in fact better cause the weight settles her down. I want 25hp and 12.5 ft though......
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Old 19-09-2014, 22:40   #25
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Re: RIB sizing for family of 4 plus med/large dog?

G'Day WB,

Lots of subjective stuff upthread, and many of the choices have no objective determinants... comes down to what you like!

IMO:
Alloy hulls are somewhat lighter. Point in fact: Our 3.5 metre Gemini hypalon Reef-Rider model weighs 47 kg bare. The flat floor aluminium hull is powder coated. The dinghy has been in constant usage for a bit over 10 years now, and the hull has numerous scratches and scrapes, but no corrosion and no issues. The Hypalon tubes are only 8 years old and are being replaced... no longer air tight. Anyhow, at the time we bought it, there were no FG hull RIBS of similar size under around 60 kg, and some well up from that. Whether that is a significant saving is up to you.

Even with a 15/20 hp motor, you don't really need a hoist on a sailboat! We've used the main halyard for this purpose with a series of 15 hp motors for many years. I've posted more detailed descriptions of this method several times if you are interested. The additional expense and clutter of the dedicated hoist don't seem justified to me at all.

For on deck storage the critical dimension is the length of the rigid hull from transom to bow, including any fabric that you can't fold out of the way. You will need to measure the distance from the front of the mast to the first obstruction on the deck. On our boat it is the baby stay. On some boats it will be the windlass, or whatever. As Ann said, most RIB salesmen have no idea of that number, so you will have to get them to deflate a floor model so that you can measure it yourself (won't make you popular!). Our RIB has a full one inch clearance! Obviously you will need to deflate it for on deck storage, and fold as much of the fabric under the hull as you can manage. We sprang for a good 12 V inflator/deflator years ago. It was kinda dear, but it means that the inflate/deflate process takes <3 minutes instead of 15 or so of awkward pumping, often of a rolling platform. A very worthwhile tool.

If you decide to tow in protected waters (and we have done that for years) one good trick is to keep a small series drogue in the dink. The big danger in towing is not bashing to windward as you would suspect, but rather going downwind with a largish following sea. The dinghy surfs much more readily than the yacht, and comes rushing up, leaving a lot of slack in the painter. As it comes off the wave, it will often slew sideways, and then slow down. The yacht continues onward and takes out the slack with a big jerk. Besides the obvious shock loading, if the cards fall badly, it can flip the dinghy sideways, with disastrous consequences. The drogue (ours has but two cones) keeps the dinghy following respectfully at the end of its painter, very much more stable in position and aspect.

As you have intuited, your dinghy is a very important bit of kit for the full time cruiser. One that is large and powerful enough will improve your life immeasurably, and is worth some serious consideration.

Cheers,

Jim
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