tuning tips for multihulls

[fastcat435]

I am worried abouth that around 20 LBS .
We try to save in every possible way even if I could find a Porcelin Jabsco toilet with a total weight of 10 kilo,s or 20 LBS including pump and stand I would still choose the RM with a total weight of only 2.7 kilo or 6 lbs each including pump that would still save 15 kilo or 33 lbs for 2 toilets.
We actually put every item on the boat onto the weight scale and compare and see if we can find another part as good in quality but with a lower weight.
You would be surprised in how much weight is to be saved like this.
Our bridgedeck clearance has come up with 4 inches from hull number 1 to hull number 5. It all helps.

Greetings and you have a good Cat

[44'cruisingcat]

Something I found very useful was to have the prodder pole mounted in such a way as to enable it to be swung from side to side, taking advantage of the wide beam of a multihull. By moving the tack to leeward we were able to carry a spinnaker at very shy angles, and in another instance by moving it to windward we could use a reacher/drifter at very square angles.

[Jmolan]

Originally Posted by gramos

fastcat , how do you keep your boats in the water! , fascinating to hear of all your weight reduction techniques , very inspiring . how can a mere mortal get the dyneema shrouds ? i am thinking of replacing mine before an atlantic trip next autumn , as its now 8 years old / dyneema , what can i use for end terminals , bottle screws etc.?

Colligonautique.com


Check out this company, they have synthetic standing rigging that a DIY or professional rigger can set up. The weight saving is 1/6 the weight of SS rigging. Very similar in price, no worries about corrosion and fatigue...well the list goes on and on....:-)

[ireaney]

Originally Posted by 44'cruisingcat

Something I found very useful was to have the prodder pole mounted in such a way as to enable it to be swung from side to side, taking advantage of the wide beam of a multihull. By moving the tack to leeward we were able to carry a spinnaker at very shy angles, and in another instance by moving it to windward we could use a reacher/drifter at very square angles.

Hi 44'Cruisincat, how did you arrange to make the pole move from side to side or did you just make it swing from a fixed position, diagrams or pictures if possible would be very interesting. Thanks

[David M]

Originally Posted by fastcat435

For the RM toilets the link is Raske en Van Der Meyde, Marine Toilets
The Link for the Lithium Ion batteries is Valence Technology | Products | Epoch Power Systems | Overview
for the Dyneema rigging http://www.gottifredimaffioli.com/en/news/news6.php
Hallo Gramos we use a Rocna 25 kilo anchor to keep the boats in the water.
A fantastic anchor down from a 40 Kilo Plow anchor used before.
Since our cat went on a weight watchers diet we have gained 30 % in speed are sailing closer to the wind than ever before and the most fantastic thing is the average speed gains with light winds are over 50 % and most of the times we have wind speeds of between 8 and 20 knots
10 knots of wind speed at 90 apparent gives us 9 knots of speed and I intend to improve on that to 10 knots of speed

Nothing like losing a little weight...live longer-go faster.

[Therapy]

Originally Posted by David M

Nothing like losing a little weight...live longer-go faster.

Is there a point at which it weighs so little that only a "small" puff at the wrong angle makes the whole thing go over like several of the models I made years ago?

[44'cruisingcat]

Originally Posted by ireaney

Hi 44'Cruisincat, how did you arrange to make the pole move from side to side or did you just make it swing from a fixed position, diagrams or pictures if possible would be very interesting. Thanks

The prodder is mounted in the centre of the forebeam, and is able to swing from side to side, controlled by small tackles. The bridle under it is led through a block on the prodder. I'll try to get some pics when I can.

[44'cruisingcat]

Originally Posted by Therapy

Is there a point at which it weighs so little that only a "small" puff at the wrong angle makes the whole thing go over like several of the models I made years ago?

The lighter the boat, the easier it will be driven, so a smaller rig and sailplan will suffice. If they are kept to the same proportions the boat will remain just as stable.

[fastcat435]

Because of the lowewr weight we have just shortened our mast with 5 ft or 1.50 meter and have reduced the sail area to 114 squire meters from 121 squire meter.
The advantages are obvious. lower center of gravity , less weight, later to set a reef
smaller moment,
we are convinced that losing weight is the best way to increase performance and bridgedeck clearance and the added bonus is extra payload . we will stay on this track. the new 405 we are aiming for 3600 kilo,s ready to sail and the next target for the 460 is 4800 kilo
She will be built in basalt fiber and epoxy resin infused.
Greetings and a good years end
Gideon

[schoonerdog]

I always loved Gideons ideas. I looked into the Margard Lexan option for our boat, but I think you would have to get a custom run for margard lexan with the thickness you'd need and tinting to prevent solar glare. But I am thinking of acrylic for our sliding glass doors. Gideon, where did you get the weighted line for the anchor set up if you don't mind my asking? Switching to 8 mm and weighted line sounds like a very achievable upgrade.

My only real achieved suggestion is after installing 700 watts of solar panels (around 100 lbs net gain as I deinstalled two 75 watt panels), I can now reduce the size of my battery bank by half. The reason is that previously I needed the batteries to last a full day at no more than 40% depleted with the tried and true technique of charging my batteries for an hour or two with an engine driven alternator. Now with solar panels I only need batteries to compensate for night time draw instead of a full day draw. So I'm able to take off two 90-100 lb batteries. I'd choose valence batteries for the remaining batteries, but being a low volume buyer they cost, I believe, 5K a piece.

[fastcat435]

Hallo Schoonerdog the thickness you require is 9.5 mm of the Lexan Margard and if you want I can help you to get it so let me know , It is my guess that one sheet of 2000 x 3000 mm would do the job this is 10 x 7 ft more or less. and this is the size it comes in . In order to gleu these sheets into the boat you need Primer G from bostik to prime the windows with and a special type of sealing Kit from bostik. that I can also get for you. We are very happy with the Marguard speccially with its self cleaning ability and the way the heat stays out.
The weighted ancor line is produced for us By the Company Liros , 50 meters costs us 250 Euro or 365 USD since we order 10 units each time together with all the other lines, I can help you here as well. The weight for the 50 meter lin is 13.6 kilo or 30 lbs
The cost of the Valence Epoch batteries is USD 1850 each with 134 amps usable power in each with a weight of 40.9 lbs each and 2 for your service is plenty this means you have 3.4 Kw available .

Warm Greetings

[jfranta]

Originally Posted by gramos

fastcat , how do you keep your boats in the water! , fascinating to hear of all your weight reduction techniques , very inspiring . how can a mere mortal get the dyneema shrouds ? i am thinking of replacing mine before an atlantic trip next autumn , as its now 8 years old / dyneema , what can i use for end terminals , bottle screws etc.?

Check out Colligo Marine for affordable Synthetic Shrouds of Dynex Dux, CSS . Worried about stretch or Creep? Check out the info on Dynex Dux. Around the same price as wire rigging and sometimes cheaper! Plus easy to do yourself.

[Gator81]

I realize that weight is probably the aspect of the cruising multihull which offers the greatest opportunity for improvements via "tuning". But there are others, as with any sailboat. One question I have for you all is: How do you "tune" your rudders? Is it as simple as making them perfectly parallel? Or is there any advantage to be gained with a slight "toe-in" between them, as there is with my little Hobie 16?

Great thread.

[fastcat435]

If the rudders are identical , have them completely in line , that saves you resistance. even With a Hobie the hobie is faster with the rudders parralel. contrary to what many hobie sailors think. I have changed my tiller arm to make them parralel and whe I Joined in the world championships in 1973 in Key Biscayne it worked fine
came in 13 out of 250 with 1 rudder broken off.

[Gator81]

It sounds like you know what you're talking about, so I'll take your word for it. On my Hobie, it's probably one of those cases where it feels faster but really isn't. I have no means of measuring true velocity on my boat. I had the rudders as truly parallel as I could get them, and the tiller bar felt very "busy", very bouncy, moving around alot. That may have just been from the additive effect of the somewhat worn connections that link the two rudders together plus some play in the rudder mounts themselves. Then, when a friend suggested that I crank in just a bit of "toe-in" into the rudders, it all smoothed out. That made it feel faster, but as you say it probably is not really faster. Thanks for the reply.