[Shinook]

I know this is a rather broad question and depends heavily on the design, but I'm curious.

If you take a traditional design cruising boat, say 30ft and 10,000 lbs, at what % of it's original weight would the boat be considered too heavy to the point of significantly degrading performance and being a safety hazard?

I see a lot of people loading up boats with gear, adding new equipment, all with no regard to the weight of the boat. I know with other things (cars, airplanes, etc), weight plays a big role in performance and safety. I'm not sure the effects of being overweight are as obvious on boats (unless you are grossly overweight), but I know it's a factor.

So at what point should it be an issue?

 

[jimgo]

When its metabolism slows and it continues to consume as much fuel as it did when it was younger.

When its BMI goes above 25.

 

[Ajax_MD]

In my opinion-

When the boat is loaded to the point where she sits on her designer-intended boot stripe, it's time to cry "Uncle!". Don't hide the problem by re-painting the boot stripe 2 or 3 inches higher.

It isn't just weight, there's windage to consider as well. I've seen boats so loaded up with radar, hard solar panels, dual wind turbines, add-on enclosures, dingy davits, dinghy outboard, that it's amazing that they function at all.

All that windage, all that weight up so high, MUST decrease stability and safety.

Some people simply cannot function without bringing their 3200 sq foot house along with them, in the form of a grossly overloaded cruiser.

 

[capt vimes]

when it sits at the bottom of the sea?

 

[christian.hess]

Ill play devils advocate...but hear me out

a LOT of boats can benefit from a little extra keel weight, a lot of boats are too tender...some boats do indeed benefit from extra ballast, especially if its in the keel sump or way down low...

Ive heard of some alberg boats and cca era boat benefiting from this...


cruising boats often times like you say are loaded badly and like you point out loaded up TOP and then they are wrapped with awesome tents and houses for the cockpit with massive stainless webs and all sorts fo gadgetry...that make it worse by creating un needed windage

there is a pic floating around here on sailnet of a "cruising" catalina I beleive with davits at least 12 feet tall and a cockpit enclosure at least 6 feet tall...added to that are panels, gear, and a dinghy...

now some of the gear is needed like panels, a wind genny(not heavy) and say what? a dingy on the foredeck or cabintop if its big enough but a lot of the gear and weight could be placed better

id hazard a guess that for a 10k lb boat you are looking at MAX 2klb(this is for decent performance not sinking! jajaja) load that includes people

on our boat of 11k on a long voyage we roughly calculated we put in 800 worth of food and supplies a dinghy that was around 100lbs including small aircooled engine and our combined weight of 325lbs...so we werent that bad at all and did not have to repaint the boot stripe.

lastly the better you position the real heavy supplies and avoid extremes on either end the better the boat will handle

I asked a similar question on a design thread and basically asked this:

would the extra ballast or displacement be of ANY benefit in ANY circumstance and about the only pro that could be thought of was less tenderness in some designs...

in almost all cases the boat will always sail better unladden with original sailplan as designed to do so...

some designs include engine weight too...for example mine does I beleive and I removed the 300 chunk of iron so it will be interesting to take notes on my performance.

my question was for heavy weather sailing basically where having more displacement and a slightly "ELONGATED" waterline would offer any better resistance or performance if you will by being able to handle slightly more wind...cause of the deeper center of gravity.

in my mind I could notice on different boats ladden or not difference in performance especially in heavy weather sailing or high wind sailing better put.

in any case

ps. I thought there was a a common formula that calculates at what load you are sinkable on any boat...

bob?

cheers

 

[Ajax_MD]

I'm a wee bit tender, when I strip the boat out for racing, but boy does she go!
I expose nearly 3 inches of anti-foul when I empty the boat out.

As you say, intelligent stowage is key to maintaining performance. I work hard to load the boat evenly, and not pack weight into the ends when I cruise.

 

[christian.hess]

oh heres a funny story I think youll enjoy

when we were cruising we befreinded a brazilian guy on a 27 footer that he was "singlehanding" with any lady that wanted to join him

his big deal was after every long passage he celebrated by trying to cram as many people on his boat for a massive and I mean massive disco party on his deck

his record was something like 30 people crammed into his boat...yes his boat was about to sink...as the freeboard was reduced by like 12 inches or so...and it was starting to wobble side to side so when that happened he said alright into the water or we sink and a bunch of naked people started jumping off like crazy until the boat was OK...

so calculate 20 people to be on the conservative side that was roughly 3.5klbs plus his cruising weight so say he had on that boat an extra 5klbs at the least before he began having stabilty issues

his boat was a 27 footer so lets say a stout 8klbs displacement that put him at 13.5klbs before issues were happening(at anchor)

that means that roughly HALF or a bit over your displacement on common cruising boats will create stability issues or sinkable issues if you will...

hope this is all taken in fun and hope this doesnt start a design or what boat is better war...

just interesting facts I learned while cruising around...

we all got a kick out of the show thats for sure! jajajaa

peace

 

[christian.hess]

I'm a wee bit tender, when I strip the boat out for racing, but boy does she go!
I expose nearly 3 inches of anti-foul when I empty the boat out.

As you say, intelligent stowage is key to maintaining performance. I work hard to load the boat evenly, and not pack weight into the ends when I cruise.

I didnt have the option of repainting my boot stripe but suffice it to say that the previous owner of my boat liked to stow stuff for sure...my antifouling is 8-10 inches above waterline give or take!

didnt help that I removed the engine either...doesnt look great but while careened was not the best time to paint on a nice stripe...

oh well!

 

[capta]

Almost every full time cruising boat I've ever seen has raised their waterline at least once, some more.
This is often because once a boat is loaded to her waterline, the topsides get pretty dirty and raising the waterline reduces this unsightly situation.
As for performance, I doubt it would make too much difference as most cruisers aren't sailing high performance vessels, anyway.
However it is a completely different story on multihulls, at least those that can actually sail; they must be kept light for safety. If you can't heel, your vessel must be light enough to accelerate quickly and alleviate the pressure on the rig, in a sudden gust. My Searunner 37 had a specific maximum weight limit, above which the vessel was no longer considered safe.

 

[christian.hess]

x2 the whole raise the boot stripe os for aesthetic reasons not to trick the mind into being a new water level. jejeje

 

[B.J. Porter]

Almost every full time cruising boat I've ever seen has raised their waterline at least once, some more.
This is often because once a boat is loaded to her waterline, the topsides get pretty dirty and raising the waterline reduces this unsightly situation.
As for performance, I doubt it would make too much difference as most cruisers aren't sailing high performance vessels, anyway.
However it is a completely different story on multihulls, at least those that can actually sail; they must be kept light for safety. If you can't heel, your vessel must be light enough to accelerate quickly and alleviate the pressure on the rig, in a sudden gust. My Searunner 37 had a specific maximum weight limit, above which the vessel was no longer considered safe.

The other reason being that once you load everything you still own onto the boat after selling 98% of your possessions, AND you pack in all the spares, tools, food, and so on the waterline...drops.

We noticed this in the roughly one week period we were transitioning from the house to the boat when we saw the waterline drop.

My boat is not overloaded, her waterline is too low!

 

[Barquito]

I think the safety of the vessel may depend a lot on how it is loaded. If it is all low it may help stability... ONLY if all your crap stays in place when you get to extreme heel. If your year supply of Chef Boyardee Ravioli rolls out of the bilge in a knock-down it will not only hit you in the head it will reduce stability.

 

[Chas H]

when it sits at the bottom of the sea?

...or when she runs aground no matter what the depthsounder reads.

 

[SloopJonB]

When you can't trim the boat properly and/or you have to raise the boot top.

My current boat had so much COTB that she was WAY down by the stern and had been repainted accordingly. Once I stripped the crap off and sold it, I was able to re-do the WL in its proper location - 4" lower - on a 30' .

 

[smurphny]

I was all set to raise my disappearing, seaweed growing, artificial reef waterline but have decided to go to an intermediate step: using Vivid white anti fouling paint to paint the existing one next time When the original waterline starts to go under, it's probably time to figure out what to toss.

 

[PCP]

Ill play devils advocate...but hear me out

a LOT of boats can benefit from a little extra keel weight, a lot of boats are too tender...some boats do indeed benefit from extra ballast, especially if its in the keel sump or way down low...

....

All boats increase overall stability when loaded but the boat AVS diminishes as well as the final stability. Performance aside a boat designer will have to ponder the two things and establish a maximum load that does not make the boat dangerous at high angles of heel or while recovering from a knock-out.

That is different from boat to boat and difficult to know without the RM stability curves with the boat loaded and unloaded. because cats don't suffer this problem they have normally a max load bigger than monohulls, even if that make them sail poorly, it does not affect negatively the stability.

I believe that even old boats have a max load established by the designer. You have just to look and search for.

 

[Shockwave]

When the waterline is nearing the cove stripe it might be time to unload some stuff.

 

[chucklesR]

Basically all boats have a designed water line, and an intended purpose and it should sit on that and be used for that.
My cruising boat (Irwin 38 center cockpit) really doesn't like to race Cal 40's around the cans, but Cal 40's can't carry 3000 pounds of stuff well.

Some designers /builders/sellers are real when it comes to producing specifications on a boats weight, i.e. they list the boat's weight with a full load, most list with an assumed half load - some try to hide by listing the weight of the boat empty.
Based on the specifications and a bunch of math my boat is able to handle 1400 pounds per inch of immersion. With full tanks and a weekend cruising load of 'stuff' she shows 3 inches of unmodified location bottom paint. Balancing the load is important as well. 200 pounds of dinghy and motor to offset the additional 150 feet of chain, heavy stuff low and centered, yada yada.
That doesn't mean I'll be loading on 4000 pounds though. I do want to sail it without having performance reduced to a barge.

 

[PCP]

...
Some designers /builders/sellers are real when it comes to producing specifications on a boats weight, i.e. they list the boat's weight with a full load, most list with an assumed half load - some try to hide by listing the weight of the boat empty.
...

Normally the weight refereed by designers and builders is normally the light weight (LW) and some times they say to what weight they are talking about. Light weight is not even the one of the boat in minimum sailing conditions, that is also some times referred as so.

Both weights are clearly defined in what regards RCD. Regarding RCD builders have also to stipulate a boat Max load that has to be on the owner boat papers (the stability curves with the boat in max load are also used for approval).

As most of the boats are today RCD approved you will find that easily in what concerns recent boats. The Max load is not given as the weight of the loaded boat but simply as the max load the boat can carry with full tankage.

Regards

Paulo