Payload of 30 feet monohull boats?

[GTom]

I am looking in the "smallish 30' " category and wondering how much useful payload can these boats take? Many are rated for high seas with 4 people on board - this means 4 tons(!) - especially when other activities like diving is planned (compressor, tanks...). Does e.g. a Beneteau 31 stay stable loaded with 4 tons??

[Tetepare]

Am I misreading? How do four people equate to four tons?


A post-race party last summer I saw 35 people on a 35' sailboat. At the dock. And it was pretty low in the water.


My friend on his Catalina 30 regularly has multiple guests with dive tanks, etc.


I don't see where four people with dive gear on a 30' boat is any cause for thought.

[Stumble]

No 30' boat is rated for 4 tons, that's getting pretty close to the all up weight of most 30' monohulls, even on a full keel heavy one 4 tons would be more that 50% of the hull weight on any boat I can think of.

I haven't looked at it, but I am guessing most 30' you have between 2,000 and 3,000lbs max payload.

[MarkSF]

Originally Posted by Tetepare

Am I misreading? How do four people equate to four tons?
.

I was aware that, as a nation, the average weight has been increasing over the years, but I didn't realise it had got that bad.

[GTom]

Originally Posted by Tetepare

Am I misreading? How do four people equate to four tons?

A post-race party last summer I saw 35 people on a 35' sailboat. At the dock. And it was pretty low in the water.

My friend on his Catalina 30 regularly has multiple guests with dive tanks, etc.

I don't see where four people with dive gear on a 30' boat is any cause for thought.

Depends how far those 4 want to sail. Puddle jump from Panama to the Marquesas may need a bit more supplies than a party (true, latter depends very much on the thirst of those racers ).

Greg: thanks, 50% of the light boat displacement makes more sense as a rule of thumb.

[Hydra]

I own a 30' monohull (3.3 tons empty, according to the papers) and I don't see where I could find space for diving gear for 4 people.From past experience, I can stow food for 4 people for about 12 days but I have only 110 litres of fresh water plus about 20 litres in bottles. In this size of yachts, space becomes a problem before weight.

Alain

[GTom]

That's correct, space will be limiting first. 4x diving gear + the smallest nitrox compressor take ~ a full cabin. It is more about challenging the "A4 -A6" CE rating, which doesn't seem indicating that a boat can hold reasonable supplies for 4-6 people for a full Atlantic crossing.

[Sailmonkey]

If we tried to put 6 people on our 32' boat for an Atlantic crossing I can guarantee I would "lose" 2-3 of them along the way.......there's just not enough room!!!

[Benz]

A lot depends on the design--a full-keel, heavy displacement hull will tolerate more loading, and sail better loaded down, than a fin-keel spade rudder model. A lot depends on layout--is a lot of room wasted on a big cockpit? Is there room wasted on an inboard engine? or batteries, inverters, refrigerators, etc?
I cruised with my family (5 of us) for five years on a Cape George 31. Even with a layout redesigned to give maximum interior capacity, things were undeniably tight. We once slept 8 people aboard (for a Panama Canal crossing), and it was really squeezy. 13 days at sea was my longest passage, with four people aboard, and that was not bad, since on passages people either want to sleep or be on deck. We did carry 130 gallons of water, and several months of rice, pasta and canned food.
Soooo, you could do it, but a lot of comfort would be sacrificed to your SCUBA gear.
Ben
zartmancruising.com

[sailingquest]

My 36 foot sailboat is documented, listed at 16 tons. Thats long tons, a measure of volume not weight. She weighs 8 tons...

[Pete7]

Originally Posted by Sailmonkey

If we tried to put 6 people on our 32' boat for an Atlantic crossing I can guarantee I would "lose" 2-3 of them along the way.......there's just not enough room!!!

Absolutely. Now the difference on our 31ft yacht between the manufacturers empty weight and our cruising weight with dinghy, outboard, fuel and water etc is an extra 700 kgs. If you increase this with food for 4 its probably 1000 kgs. Add 4 people at 150 kgs including personal items plus diving kit and a small compressor, you are up to 2000 kgs.

That 2T might cost us an extra inch on the water line and be acceptable, but as pointed out finding space will be interesting. Take the table out and out a bottle rack in place perhaps. Put the compressor on the fore deck to balance the 4 people who will probably be spending most of the time in the cockpit.

However, yachts are crap to dive off, get a decent dinghy and dive from that.

Pete

[Stumble]

Originally Posted by GTom

Depends how far those 4 want to sail. Puddle jump from Panama to the Marquesas may need a bit more supplies than a party (true, latter depends very much on the thirst of those racers ).

Greg: thanks, 50% of the light boat displacement makes more sense as a rule of thumb.

50% is not a rule of thumb, in most cases it wouldn't be a grossly, probably dangerously overloaded vessel. On the average 30' boat I would guess you have less than 2,000lbs total load capacity. Including fuel, stores, people, supplies, and dive gear. Maybe more like 20-25% of lightship displacement. Adding more gear means you are overloading the boat, possibly dangerously so. Which could lead to all sorts of issues, not least of which would be snapping the mast.

But if you really want to know subtract the lightship weight from the max displacement. That's your total allowable crew+stores+fuel weight.

[Tom--]

Sailboat calculator 3.55 says the Catalina 30 requires 967Lb (440kg) to immerse an additional 1 inch (25mm). The Cape Dory 30 requires 773Lb (351Kg) to immerse an additional inch (25mm). The Beneteau 305 requires 1025Lb (466Kg) for same increase in immersion. Waterline length and beam help define a boat more than length overall. Displacement says a great deal too. This weight per inch of immersion is not completely accurate as each additional inch increases length and breath. Thirty feet fills up fast.

Sail Calculator Pro v3.54 - 2800+ boats

[Barefootnavigat]

I can carry 3,000 lbs in my 22'er, her net tonnage is a smidge over 5, everything goes in its place and Im still not at my LWL. she works fine for 2, "light-bulb moment" actually Im single so maybe that's a sign that she is best for one but i have happily cruised extensively with 2.

[Pizzazz]

I just made a quick calculation based on the hull shape of my Hunter 31 (9,700 lb dry) showing that 1,000 lb of extra load is approx. 1" increase in draft. I would say that one can safely go 2-3" below the waterline for a 2-3,000 payload on top of the standard (which is probably around 2,500 lb). Thus, the 50% of displacement rule is closer to the truth. Easiest way to check is to get a large party on board and go sailing close to shore noting how the boat behaves in different wave/wind combinations.

The reason why we get so many different views on this is that people have different perceptions of risk and tend to emphasize worst case scenarios. For example, 90% of time boats sail in less than 15 knots of wind and with 1-2 people aboard. If you regularly have 4 people on board you need a bigger boat. If it is a once in a blue moon trip just make sure you are good friends before the trip (you will not be good friends after either way). I would not regularly sail with an overloaded boat 3" below the waterline but it can be done (and you can always lose the extra equipment in an emergency). Only you can determine how much trouble you want to put up with and for how long.