Weight Reduction 2015

Weight Reduction

Multihulls, trimarans in particular, are weight sensitive.  In comparison to a monohull, they are generally considered to be overpowered for the weight.  Ever watch a beach cat, NACRA for instance, sail circles around a big monohull?  Strider is 33 feet long and is 5,100 pounds empty.  For comparison, a 31 foot Beneteau Sense is 10,670 pounds empty.  Strider is a light boat! 


This all started when I received a quote by Jens Quorning, the manufacturer of the Dragonfly, forwarded by a friend exploring the DF 1000:

"The DF 1000 was originally designed for coastal and offshore cruising.  The DF 1000 is not designed and built as strong as our designs today – where we today have much more knowledge in design and production. The DF 1000 was designed back in 1989/90.  I cannot recommend the DF 1000 for ocean crossings or bluewater type sailing.  The problem is that the boat is heavier than it was designed for."

The first thought was about the last line:  "Heavier than designed for...."  Understandable, but unsettling.  The second thought was regarding how technology has changed since 1989/90.  What is available now that wasn't available then?  These beg the question:  "How can weight be reduced and therefore improve performance and presumably, safety?"

For clarification, there does not seem to be much older boat support from Quorning.  Hell, the DF 1000 is not even on their website, nor is a support page.  Sure, they will sell you something, if the stock is on hand and you want to pay their prices (45 euro for a locker hinge or $2200 for a set of waterstays).  Forget engineering support.  So I took this on myself.  For further clarification, I've an Aerospace Engineering degree with structures being a focus.  I've some practical experience.  Further, I know how to research.  That said, none of the below has any kind of certification.  DISCLAIMER:  I'd be happy to provide details, but if you follow, you are on your own.

Creature Comforts:
As my mentor Steve has mentioned:  We also fall prey to the creature comfort weight addition syndrome.  A watermaker adds 60lbs.  Food, utensils, tools, clothing, crab trap, fishing gear, cleaning supplies, a couple sails, stern tie, better wiring.  You get the picture.  All these things to make life easier or more comfortable, but a heavier boat.  The easiest weight reduction is to purge your boat.

Hull:
The fiberglass and structural stainless steel are what they are.  Unless one can replace structural stainless with titanium or aluminum, there is very little to be done to reduce hull weight except ensure the non-hydrophobic foam core stays dry.  If water can intrude, it will be absorbed by the foam, increasing the weight.  So, to help prevent water intrusion, Strider's hatches and rails are being reseated using the technique explained in this Maine Cruising article.

There are other small things.  Like putting lightening holes in some of the wood panels.  Lightening holes?  1-2in holes cut in the wood panels, making them look like swiss cheese.  Like the panels in the V-berth, most of the panels are not structural, but are covers over storage areas.  They can be 'holed' easily.  While weight reduction is minor, the air circulation benefit is huge.

Replace 1/4in plexiglass windscreen with 1/8in acrylic.  Replace vinyl and rubber water lines with PEX.  With the exception of keeping the foam dry, the above are small things:  a pound here, a couple ounces there.

Add-ons:
What could have a bigger effect?  This is where the latest technology really helps.

Strider came with 3 Optima Yellow Top batteries, one start and two house.  I followed Steve's example and replaced the 3x44 pound batteries with 4x12.5 pound (132lb vs 50lb), LiFEPO4 batteries.

More weight reduction can be achieved by replacing stainless cables with synthetic line.  The best part is I can do it on my own!

A note of caution:  The cable replacement was not done all at once.  Since something new can be risky on a sailboat, one step at a time.  Paul Calder's articles on replacing stainless with synthetic were very helpful.

First, the waterstays were replaced.  Details are available here.  Essentially, one of the waterstay fittings was corroding and cracking and I balked at paying Quorning's price for replacements.  New waterstays were fabricated after research into stainless vs Plasma break-strengths/stretch-characteristics, a local rigger's assistance to learn splicing first hand and locally acquired materials.  Colligo Marine's lashing tie off instructions were followed and they allow for easy adjustment, which was necessary as the plasma/dyneema settled in.  This took a while and I cringed when larger wakes and waves approached.  38 pound reduction.

Once satisfied, the nets and aka cables were next.  While still not pretty, the net edge finishing is a work in progress, the Net-Systems Ultra Cross was selected.  I was concerned my dogs would not like the new net with the larger holes.  The couldn't care less and may actually prefer it as one spends his time on the net now and not on the solar panel.  Another 38 pound weight reduction.

As of this writing the backstays are being worked on, replacing the stainless and the blocks.  While overkill in strength, 5/16" dyneema is used because its stretch characteristic is the same as the replaced stainless.  While only partially complete, the 4:1 backstay adjustment system has yet to be replaced, the main section has been replaced using Colligo's chain plate distributor at the bottom, a simple 8mm thimble at the top.  The stay side adjustment block and large quick link between the upper and lower stay have been eliminated by using Colligo's double enhanced lashing block.  The upper and lower backstay components are spliced through the center of the block while the adjustment line goes around the outside.  22 pounds weight reduction.

Coming soon; the mast supports/shrouds.  There is a lot of stainless cabling on the mast.  Reducing this weight will reduce the weight aloft and decrease the hobby-horse effects.

To date, the weight reduction has been:

Stainless Cable Replacement:

Waterstays:  38 pounds
Aka:              2 pounds
Backstays:  22 pounds
Shrouds:     Not yet....

Other Sources:

Batteries:     82 pounds
Nets:            38 pounds

Total:         184 pounds!