Placement of heavy items - low or high?

[psneeld]

By using up consumables, the boat generally gets more rolly but if designd well....not dangerous. I believe large cargo vessels going to sea ballast with sea water...well they used to...I lost track after ballast water became such a contention with pollution and transporting non-native species organisms.


I took 3/4 of my fuel tankage out (300 gallons plus big thick steel tanks and put in 2-50 gallon poly tanks). My boa is riding higher in the water but I can't feel or see a difference on the inclinometer in thousands of miles of travelling.


The weights added or removed in non critical places can be pretty significant without changing stability too much. A much smaller weight in a critical are can have much more effect. But that weight has to be significant enough to begin with in comparison to the whole boat.


As pointed out, exacting measurements are truly needed for accurate assessment but other things should be telling a reasonably seasoed skipper what is OK and what isn't.


I am sure 139 pounds is flyshi* under my flybridge fairing. If I can hang my 150 pound dingy out over the side on my boat from a 4 foot higher boom an 4 feet wider than my beam...and hardly notice the list...I am pretty "backyard confident" my stability won' be the issue in rough enough seas to matter...it will be injured crew blown out windows, power loss...etc...etc...


For those with true seagoing boats or plan to take their TT to sea, an accurate stability test/data sheet and sticking to a storage plan would be prudent.

 

[AusCan]

I am very careful about where I place my movable weight. (tool boxes, spare anchor, deflated dinghy, spare parts) I try to keep it as low and central as possible. Perhaps I notice the listing more than most, having a rounded bilge, whereas a hard chine boat sits much flatter in comparison until things are very much out of balance.

With the unpredictable water & weather we get I don't like to push my luck with the boat's stability.

 

[sunchaser]

I am very careful about where I place my movable weight. (tool boxes, spare anchor, deflated dinghy, spare parts) I try to keep it as low and central as possible. With the unpredictable water & weather we get I don't like to push my luck with the boat's stability.

From my sailing days I learned the same. Weight placement wins or loses races. When participating as crew during the Lightning Jr Championsips I was booted off by the eventual winner when winds got above 15 knots. My replacement outweighed me by about 70 pounds. I was the light air guy.

There is no downside to placing movable weight low. Heck, I even stow all large containers of cleaning products in the bilge, anal I know but weight placement can be a race winner.

 

[psneeld]

All great points...but certainly the weight in question has to be compared to the weight of the vessel....


130 pounds in a canoe vs the USS Nimitz.... perspective is a good tool when not able to do the actual science of it all, just being a simple operator.


I'd hate to scare any new big boaters from enjoying their flying bridge with a few friends when some make it sound like 130 pounds is a big deal....even just HAVING a flying bridge.

 

[Nomad Willy]

There's lots and lots of boaters that go racing across the bay listing 10 degrees or more seemingly unaware. AusCan is prpbably not one of them and like him I am careful about where I put weight. We can all lean toward excellence or lean to (in varying degrees) any old way. Some would consider me quite sloppy in some ways. A skipper placing weight in it's propper place is a mark of excellent seamanship.

 

[psneeld]

An excellent skipper knows where the weight CAN be placed that is relatively insignificant in the big scheme of things.


If things can be stored low, fine, but not everything can be or should be because they will not be used due to inaccessibility.


Anybody can be told to store weight as low as possible....it just takes a moment to realize what is a threat to stability or not based on some simple clues or judgment calls. It in NO WAY insinuates a person is not an excellent skipper.

 

[healhustler]

When it comes to weight above the CG, I probably (as mentioned by PSNeeld) think too much. One of the first projects I had to do on our boat was rebuild the pilothouse roof. Incredibly, I ground-out somewhere around 110 lbs. of glue of which maybe 35 percent or was actually adhering the inner and outer skins of the roof. I re-skinned with a new panel and pumped the roof full of 7 lb. foam, figuring I saved about 85 lbs. total over the original setup. I have new reduced-size pilothouse windows being built now which will save another 45 lbs. over the original, including thicker aluminum framing added at the post areas. Some of that advantage has already been negated by the weight of a custom mast and new electronics, now centered about 16" higher than it was when mounted on the roof. The rest of the advantage will disappear when I finish mounting the solar panels.

All one can really do is to be conscious and reasonable about adding weight above CG while considering the use of modern materials to save a few pounds when you can. These days, accessory weight can really pile up. A single marine rated roof-top A/C is 175 lbs.. That's another average guy standing on your roof!

I tend to go with PSneeld with the evaluation of the OP's basic question. 130 lbs. is not something that should weigh heavily on the mind of an owner of the average journey for the average TF coastal cruiser, but in crossing the Gulf of Mexico or heading for the Bahamas, it seems only prudent to store heavier items below.

 

[dimer2]

Perhaps I should clarify my earlier post regarding my "500 lb dinghy".


I have a 750 lb swl OEM crane and the dinghy sits on the OEM installed chocks and therefore feel I am well inside the OEM weight criteria (at least I hope so!). I would be concerned with adding an additional 500 lbs up top. I still don't feel the difference in roll in having it up top or towing it but as Tad points out, I probably won't until it's to late....

 

[psneeld]

Sure you will notice it....maybe not once over at 90 degrees...but boats like ours have limited survivability in those kind of situations.


If out in a decent seaway...and your boat rolls...but rolls right back...the stability is fine. When it is starting to get sluggish at some point in the roll...that's the early warning sign.


If you have any doubts....have someone check it out...either someone with practical experience you trust or a professional that has all the tools to be exact.

 

[BrianSmith]

For purposes of this discussion - the boat is 53', is steel from the keel to the upper deck, and weighs 83,000 lbs. So that 130# scuba compressor on the FB probably isn't going to matter. But I have options, and until we take possession of the boat, I won't be able to make a decision.

Thanks, as always, for all the input.

 

[psneeld]

Bingo...I was basing my input on a 43 Gulfstar...


A 53'teel vessel at 83,000 pounds?????...I'm not sure a 1300 pound compressor would raise eyebrows in the world I am used to....

Not unless the boat was a clusterf*** to begin with.

 

[Nomad Willy]

A 40 ton boat?

Even I would put a 130lb thing on that FB.