All posts by Kurt

Chaak Pic Again

Chaak recently popped up on the Classical Sailing Multihull page. After she ran hard on the beach, destroying the original amas, I was asked to design new amas and beams for Chaak. ’85 maybe? They have proven to be tough. It did a run to Hawaii and back. It was campaigned harder than most PNW boats at that time. I recall Tim mentioning one time when the route back from Hawaii was by way of Alaska. Tim started to realize that when the shadow parted from the boat every few waves, it meant they were airborne.

USCG aircraft above asked if then needed help. “Nope”.
I recall that there was a Constant Camber 44 designed that was supposed to beat Chaak in racing. In fact it was nicknamed “Chaakduster”. Was not even close.

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On the Way to the NEMA Event

I rode down to the event with former crew and amazing sailor David Osteen. As we were leaving a marina, he spotted an ama sandwiched up on the hard in between a dozen varied craft.
We got out for a closer look. It was my 46 performance tri design Pipe 3 (formerly Faamu Sami).  It was the first time I have seen the boat.

Quemarla Has a New Home,

Back to it’s first home after a lap around the world.

Nice note from the new owner, Paul.
“Paul Willison
January 6 at 4:46 PM
When Kurt Hughes designed this boat he really got it right. Tacking strongly into big Western Australia seas and wind. We are comfy and dry and pointing high biggest problem is trying to slow down. Thanks Kurt”

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Speaking at NEMA Dinner

A nice note from Andrew. I hope my builders in the area can show up and talk about their projects.

Kurt Hughes, Multihull Designer

Kurt Hughes, a prominent multihull designer and builder based in Seattle, Washington, will be our annual dinner speaker at the Cambria Newport Atlantic Hotel, February 2, 2019.
Kurt has a long list of significant multihull designs that are scattered around the globe, including trimarans, catamarans, and proas, both sail and motor powered. He has also lectured extensively on composite construction techniques and multihull design. He’s built three substantial trimarans – 26, 32, and 40 feet—and a 23 foot proa. And he’s applied composite boat building skills to the construction of a “lunar lander,” a “retrofuturist tiny house being built using advanced boatbuilding methods.”
Kurt will talk about the history, development and construction of his designs and take your questions about what works on the water and in the construction process.
We will also have our seasonal trophy awards, good food, a cash bar, and we expect some North Sails swag will be available. You can register at the hotel at, or call 1 401-236-2020. The hotel is giving NEMA members a special $99.00 room rate on Feb. 2, so you can check in and enjoy yourself without worrying about the drive home Saturday night. Register for the annual dinner through the website. We look forward to the annual gathering, some tall stories about the 2018 season, and seeing friends new and old.

Andrew L. Houlding ”

They have an amazingly luscious newsletter.  .

And in the group photo a ways down, what a crowd of multihull celebrities. I will be so honored to be talking to them.

Is Bob Smith Missing?

Is This Catamaran Missing?
By John Arndt | December 17, 2018 | Sea of Cortez, Mexico | 0
Former Latitude 38 editor LaDonna Bubak just alerted us to a Cruisers Forum note that cruiser Bob Smith, of the home-built 44-ft catamaran Pantera, hasn’t been heard from in three months. His daughter, Natalie, has become concerned. Natalie reports that Bob has been living aboard in Mexico for the past 10 years. He typically remains in touch on a regular basis. Brad of the SV Perspective reports seeing him on October 19 on the Bay of Los Angeles in the Sea of Cortez with all well.  Pantera is an active, well-known cruising cat along the Mexican coast, and a vet of the 2006 Baja Ha-Ha. We just want to help put Natalie’s concerns to rest.

Bob was in my office a dozen times as we did the design.  At the dawn of CADD. Hope he is ok.

Unfolding Hull Panels

Busy day today. Unfolded the chine panels for the 30′ catamaran workboat. Rhino 6.
Used to be I would just plot out the patterns. However, my nearly new Canon plotter that cost about half the price of a Honda Civic quit and they tell me it will be expensive. So for now I dimension the flat patterns.
Leaving HP was probably a mistake.

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More Electric Cat

The second note from Kevin.
“Hi Scott,
Here’s the results with the pulley changes. I will call shortly to discuss.

10/21 Re-test
Installed 18 tooth pulley on QT10 (port), and two 20 tooth pulleys on QT20 (stbd).
QT20 display always shows “Key on” regardless of position, but doesn’t show “hours”.
QT10 display doesn’t show “key” at all but does show “99 hours”

Boat is still very light with no water or equipment etc aboard. Bottom clean.
Running perpendicular to a 14knt breeze in flat water.
Port QT10 running alone achieved 139amps, 1460rpm on power setting 100, going 5.6knts
Starboard QT20 running alone achieved 341amps,1844rpm on power setting 76, going 8.2knts
With both motors running: port got 152amps at 1700rpm, starboard got 353amps at 1875rpm with a boat speed of 8.7knts

Running port only at 100amps achieves 5.5knt
“ Starboard “ “ “ 5.8knts

Running one motor at 50amps gets 4.5 kits
2motors at 50amps each gets 5.5

Running both at 100amps each gets 7knts and when running into the 14knt breeze that was reduced to 6knts.

Reduce pulleys more or re-prop?

Thanks, Kevin”

Electrical Install

I was fortunate to get Kevin’s notes from going electric on his 48′ cruising cat.

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“Hey Kurt thought you’d be interested in my notes from my first tests with electric motors. Overall pleased so far, but this is not for most people. The complication is high and needs to be self installed to understand. Actually the motors are easy…Its just the entire system integration that’s hard. I’m off to Europe for a month so won’t get any more info for a while.
Cheers, Kevin

nitial testing motors: All needs redo….Got amps wrong on both motors, need smaller pulleys.

Boat is very light with little equipment and no water etc. Clean paint.
Approx. 14-18knts breeze.
Motoring out into breeze on batts only 7.5knts easy to achieve. Uncertain of total amp draw as port motor not reading shunt. She felt much stronger into the breeze than my old 16hp diesels which I attribute also to the 3blade 18” props vs old 16” 2blades props.

STBD motor (alone) once set is running at power setting 50 achieving 1500rpm @ 250A
Was possible to run 300A+ but dialed down to spec. Scott I screwed up on this one. I had 250A in my head— not 350A per manual. That said, I think I will need the smaller pulley to get the numbers . This highlighted sentence skews all the rest of the numbers on this page of course since everything is based on 250A for starboard and 125A port

Port motor (alone) on power setting 95 got 1300rpm @ 123A (using clamp on amp meter). Scott I guess I need the smaller pulley for this motor to get my 1700rpm and 175A

Running STBD alone at 23A (just above idle) perpendicular to breeze got around 3.3knts which should get just under 10hours on batts alone. But this was in strong cross wind….

Top speed with both motors was 9-9.3knts at 375A…roughly 18.5KW (50v x375a)
So should have about 36m of full power available. This exceeds battery output specs so wouldn’t do this without genset backup. Adding the full 250A from the genset should allow 1.8hrs of full speed before that batts give up. Scott are the motors ok with this if for some unusual reason I wanted to use them this hard? (This question to be adjusted to 350A…)

Did not test amps vs. speed vs. 1motor vs 2motor yet to create efficiency chart.
I suspect 100A on one motor, vs split between 2 motors, will yield higher speed in flat calm but the opposite will be true into a breeze or chopped water. Too be tested.

On the delivery run, when motors were not dialed in, I ran the genset for an hour with the boat cruising at 7.5knts into 10-12knt headwind and saw no voltage drop on the batts. On my old diesels I could have achieved 7knts in the same conditions but they would have been working hard. More typically I cruised at 6.5knts. So very happy with this result but haven’t compared fuel yet.

Setting regen at 100 allowed the props to stop spinning! No shaft brakes needed so far.
This is a big deal for fast boats like mine.

It is very easy to loose settings while adjusting on display. I do not love the displays! Running both motors on one display pointless. Two is much better.

Started testing with 53.5v. Motored out into trades then did 5 or 6 runs back an forth across bay at various speeds. Returned to mooring with 52.5v still in the tank.

Shifting is very different than diesels. Slower response. This makes maneuvering a boat like mine onto the mooring in breeze challenging. I have plenty power but it takes much longer to from forward to reverse. Something to adapt to

Reverse has too much power on both motors! Would like to decrease reverse power. Just a tiny bit of throttle way revs up! Scott any options here? It will be worse with smaller pulleys.

Scott’s performance predictions graph indicate 19kw [my current max output, depending on whether one uses 50v or 53.5v x (123A port + 250A starboard) will push the boat at 8.2knts. Actual speed seems to be 9knts on initial test.
So Scott seems right or better on speed.

Distance, however is poorly predicted simply because 300AH is bad input. Actual available power is only 225AH because batts only receive 90% top charge and cut out at 15%DOD.
My numbers above, 3.3knts @ 23A with 225AH available, indicate a 32 mile range vs. 41 miles on Scott’s chart (corrected for actual AH available). But test was with strong cross wind and run over short distance so better numbers needed.

At 9knts range would be something like 4.5 miles which is very close to roughly 5.25 miles on Scott’s chart corrected for 225AH.

If I had gone with 2x QT10’s I would have had 13kw of max power. Estimating from the chart vs. current actual speed I think my top speed would have been 8knts and somewhat less authority at lower speed.

2x QT20’s probably would scrape a weak 10knts top speed.

Speeds will probably not change much when I load the boat as I have found this doesn’t slow her down much accept in acceleration.

Kevin Millett
Holo Holo Charters

phone: 808.335.0815
physical: 4353 Waialo Rd. Ste 5A, Ele’ele HI 96705
mailing: PO Box 50940, Ele’ele HI 96705