Multihull Weight Saving Stratagies

[jdazey]

Originally Posted by swanpol

best for weight saving,,
cruise solo, leave your wife at home¡¡¡¡
dry boat , no beers or alcool,,

No fun!


Cheers,

[thinwater]

I strongly considered Sleep Number mattresses for my last boat but never got around to it. I have had them at home for ~ 15 years. They make RV models that are lighter than conventional foam mattresses and far more comfortable. Very handy if there are lockers under them.


I've heard of people using air mattresses on seats, but that is totally different (local pressure vs. spread out).

[owly]

I get the feeling that most folks really don't know what they have aboard for payload, what the payload of their multihull really is, etc. When you look at the empty weight for any multihull, and what is included in that weight and what is not, and start adding up what you are putting aboard, it's amazing how rapidly the payload gets eaten up....... How many people here really know what their boat weighs empty.... in real life, and loaded in real life. It would be my guess that very few multihulls are operating within their rated displacement...... ever. This is significant in terms not just of performance, but structural concerns, and bridge deck clearance. In really rough conditions there is danger of structural damage or failure and even breakup..... it may be a trivial issue for coastal sailors, but it's not for those who are liable to face extreme conditions at some point.
The GGR or 1968 is being "reenacted" this year, and it should remind us that the two trimarans that sailed in the 1968 GGR both suffered structural damage, and it still happens today.



By the way someone suggested no alcoholic beverages as a weight saving measure. Someone should point out that 80 proof whiskey weighs 7.5 pounds per gallon and water weighs 8.34 pounds per gallon. Take whiskey instead of water and save almost a pound per gallon ;-)


I've been an advocate of ice as a battery for a long time..... Make ice while the sun shines using solar energy. That ice will refrigerate your food for a long time and the refrigeration system needn't mindlessly cycle, sucking down battery capacity. Some marine refrigeration systems are built this way......... "cold plate" refrigeration. High gravity micro brews in cans make perfect ice cubes at well below the temp of ordinary ice, and won't rupture like lower gravity brews will. This is a high efficiency "battery" that will never wear out, and is lighter and cheaper than ordinary batteries.


The charts on lead acid batteries show that the life expectancy of deep cycle batteries is based on how much energy is stored and recovered over the life of the battery. We need to look at battery life in lifetime kilowatt hours. Discharging a battery down to 20% charge as opposed to the recommended 80% does reduce the lifetime KWH of the battery, but only by about 20%. What that means is that you can carry fewer batteries / less weight, and the result will be more frequent battery replacement............ In the end the replacement cost will run about 20% higher over time, but the gain will be perhaps 25% less battery weight. The additional "benefit" will be that you will not be faced with a huge outlay to replace a large bank all at once, but a fairly manageable annual expense.

Ultimately if you are sailing in US waters, if you size your battery bank such that it will need replacement every 10 months for example, that will fall within the one year free replacement warranty of Batteries Plus for their deep cycle batteries, and one should be able to operate at virtually zero battery replacement cost.

Thus you gain both on weight savings and replacement cost.......... a win win situation!!


H.W.

[Training Wheels]

Originally Posted by thinwater

I strongly considered Sleep Number mattresses for my last boat but never got around to it. I have had them at home for ~ 15 years. They make RV models that are lighter than conventional foam mattresses and far more comfortable. Very handy if there are lockers under them.


I've heard of people using air mattresses on seats, but that is totally different (local pressure vs. spread out).

All our cushions are starting to need replacement. Actually was thinking that custom made inflatable cushions and mattresses might work well, and save a lot of weight. Seems like it would make for cooler sleeping in the tropics.
Anybody done this or know of any place that makes custom made inflatable mattresses?

[Shaneesprit]

We need to know the boat and the issue?
Previously had a 30ft CAT ( dads not mine ) that had its water line repainted, it wouldn’t sail even under power it was struggling, didn’t know why until he spotted the wash it was leaving, everything went even pretty over sized door catches and 3 ways of making power. Lots of space on a CAT just enjoy the space don’t fill it.
I am actually moving weight forward this winter.

[LifePart2]

Easy,

Switch out your lead batteries for Lithium: How to install and maintain your lithium house batteries

Switch your steel rigging for Dyneema Dux

Switch your 800 litres of water tankage for a watermaker. (but still carry enough on a passage in case the watermaker breaks.)

Just with those three you have saved probably 800 kg all up.

Then cut your toothbrushes to half length to save another few grams

[Catmandu]

If you have to have air conditioning, consider implementing a "buffered" inverter-based electrical system. you can cut a bunch of wt. w/smaller gen set and smaller lithium bat bank to absorb the spikes ... save you 3-400kg.

[thinwater]

Originally Posted by Catmandu

If you have to have air conditioning, consider implementing a "buffered" inverter-based electrical system. you can cut a bunch of wt. w/smaller gen set and smaller lithium bat bank to absorb the spikes ... save you 3-400kg.

I did that. It's just good engineering. Helpful even when shore power isn't all that it should be.


I've got to believe LiFePO4 batteries will be standard on cats soon. The weight is only part of it.

[Catmandu]

Originally Posted by thinwater

I did that. It's just good engineering. Helpful even when shore power isn't all that it should be.


I've got to believe LiFePO4 batteries will be standard on cats soon. The weight is only part of it.

Yes, there is so much effort being put into LiFePO4 battery technology (e.g. Tesla) that eventually these will be standard for cats if not all boats.

IMHO its not quite there yet so right now I would take the slight hit on wt. and go carbon foam instead of LiFePO4.

[a64pilot]

I’m not a multihuller, but the Tesla comment I have to answer.
Tesla is and has been a hugely successful marketing thing, however they have done not much for battery technology, the cars literally are run from thousands of Panasonic 18650 flashlight battery cells. Yes those cells are used for other things than flashlights, but Tesla hasn’t done any battery development.
Plus they are Li-Po not LifePo4.

Now the other auto manufacturers, are, or likely will develop and or push battery technology.

[dancor01]

Originally Posted by thinwater

Not to include more carbon fiber and foam. I'm thinking things that are easily changed.
Clever ideas?

First I would need to know how long the boat is.
Second if it's a tri or a cat.
And third crusing or racing?

[thlamers]

We sail a 26 foot cat for about 60 days per year so have to keep weight down while living aboard.

Replace books with Kindel where possible.

Switch lines to high strength, fast drying equivalents. A wet Nylon anchor rode is quite heavy. Eqivalent strength polypropylene holds almost no water and floats

Skip the dink motor and learn to row.

Weigh everything on board to find out where the opportunities are.

Carry less food to loose weight.

Chat de LaMer

[billyehh]

A lot of these ideas are OK if you are a coastal cruiser along a First World coast. If you are in the Caribbean a lot of things are not available or have to be shipped in at Great expense (FedEx) or take a long time by sea not including the bureaucracy of clearing it through Customs. The average cruising cat is not a performance boat and its crew is usually looking for comfort because they spend 80 to 90 percent of their time at anchor or in a marina. I tend to be on the hook because I like to have a swim first thing in the morning.

That said there are a number of good suggestion in this thread. One of my favourite is going through the locker and deciding if something is useful. I try to have a rule, that if something new come aboard, something else has to go. Being a cruiser this is not always followed.

ANCHOR AND CHAIN. I have a 25 kg Delta at the bow, but the 60 metres of 3/8 chain is stored in a locker near the mast. I may be old school, but safety comes first. Also most other boats have a similar setup and everyone tends to swing together in increasingly crowded anchorages.

DINGHY I have a 9 1/2 foot aluminum bottom RIB with a 10hp 4 stroke engine. The total package weighs 185lbs and fits between my hulls with the motor. Your dinghy is your transportation at anchor and it pays to have reliable one. I actually spend more on fuel for the dinghy than diesel for the catamaran during the season.

SOLAR PANELS I bought good quality Japanese solar panels 11 years ago and though they are 1/3rd the price now, it is the best upgrade that I have made. There are 520 watts of panels and a battery bank of 690 amps. I looked at LiFePO4 batteries last year and decided to stay with AGM's. The weight savings was just over 100kgs but at a cost of $5500 compared to less then $2000. This does not include the cost of new charging regulator for my alternators and 11year old mppt solar controller. My battery charger is new last year and is compatable

REFRIGERATION The best insulated box is a power and therefor weight saver. My system uses the old Cold Machine Danfoss compressor. It is air cooled. I added a computer fan to dissipate heat and it works very well. No water cooled system with its pumps and holes in the hull.

You see. Just keep on plugging away and you will find some savings in weight, but remember why you are cruising in the first place. Otherwise, win a lottery and it won't matter

[sailorcherry]

Originally Posted by LifePart2

Easy,

Switch out your lead batteries for Lithium: How to install and maintain your lithium house batteries

Switch your steel rigging for Dyneema Dux

Switch your 800 litres of water tankage for a watermaker. (but still carry enough on a passage in case the watermaker breaks.)

Just with those three you have saved probably 800 kg all up.

Then cut your toothbrushes to half length to save another few grams

LifePart2, what's the current cost difference between the lithium or agm. Say for something like a Gemini 105? Basic systems, propane powered fridge and let's imagine no a/c (or instead use genny for a/c).

[Bill_Giles]

Good heaven, when people are sailing the Atlantic in boats smaller that 6 feet long, you are trying to lighten your boat? So let us talk about towels. When cruising I have one quick dry towel, none of your thick, fleecy, snuggly things. And a wash cloth or sponge. So just shower, use the wash cloth to wipe down, wring out, wipe down etc. Then the towel can “fluff dry” you. A wrung out wash cloth and towel dry instantly on the guard rail. And if the wash cloth is damp next time around who cares?