Hey guys don't feel bad.

My mate just sent me this for Christmas.

I thought he was a nice bloke too.

That is a great result, shows that there is an alternative avaible to get yachts sailing. The price of second hand wind surfer mast is reasonable and aviable where as ali masts are almost impossible to buy in Aus.

Just a question I was asked and did not know the answer. What do the numbers on the fiberglass/carbon mast mean and what numbers should we be looking for to suit class5.

Water yacht dinghy masts are NO use in either Class5 or Mini 5.6m classes, as BOTH specify it must be a 'round' mast section (dinghy masts are not...with the exception of the Laser) and normally way to thin in wall thickness.
Water Yacht sails are NOT suitable for LandYachts either as they are way too full in shape which gives lots of power but very little speed, sailboard sails are MUCH better for LandYachts.
The best you can salvage from water yachts are the pulleys and maybe the sheet rope......

AUS230

Numbers on windsurf masts, there will be a few:
- Diameter, SDM - Standard Diameter, RDM - Reduced Diameter, we want SDM
- Carbon % usually the higher the better
- Weight
- length
- IMCS is a measure of mast flex. Higher = stiffer. The mast I just bought is rated 37 as you can see in the pic this is very close to Paul's ally mast. 37 is very stiff for a windsurfer, think special race masts, cost a fortune new and rare as second hand but they're out there I found one :)

Translated some info on masts from a Belgian surfforum, autor Willy B18.
MCS and IMCS (mast check system and indexed mast check system)
Is easyly a way to indicate the stiffness and flex of a mast. A higher number indicates a higher stiffness. In 99% of nowadays masts you can divert the stiffness from the length of the mast. In this case a 460 mast shall mostly have an IMCS of 25, irrespective of the %carbon.
IMCS can variate from 9 for a 370 kiddy mast up to 40 for a 580 FORMULA mast.
IMCS is based on the older MCS.
IMCS and MCS are related.
MCS is a way of measuring that allows to compare stiffness and flex of masts.

From an answer in the same topic (by Jeroensurf)
370 = 17 IMCS
400 = 19 IMCS
430 = 21 - 23 IMCS
460 = 25 - 26 IMCS
490 = 27 - 28 IMCS

I hope this makes something clear about IMCS and stiffness and flex. If you want more, I can translate a lot more about masts and measuring.
Merry christmas and a windy new year.

How the Flex is measured.
Put the mast in horizontal position on two points with little friction at 5 cm from top and bottom.A weight of 30kg is hung in the middle of the mast. Then the bending of the mast is measured at 25, 50 and 75%of the mast.Two other important things are the bending of base and top
The formula for the bending and the MCS value:
MCS = (length of the mast x 10) / bending at 50% of the mast length
Base % = (bending at 25%) / (Bending at 50%)
Tip% = ( bending at 75%) / (bending at 50%)

IMCS uses a 460 cm mast as an index. When you have the MCS of the mast, you'll find the IMCS by using the following formula:
(MCS x length)2 / (MCS)2

there are 2 types of masts: constant curve and flex top.
constant curve: 76% bending in the top and 65% flex in the base. They are referred at as 12% constant curve masts.
flex top: 82% in the base and 62% in the top. Known as 20% flex top masts.
info came from the same autor as above

looking good.

quite impressed with the seat today john, I plan to add some of your changes to my own work

Yesterday I got the Jig and my land yacht parts.

Up early this morning 3:30am got some welding lessons from my teacher Steve Bleile.





Started fit up and assembly of Class 5 chassis no.3 from the jig.

I spent 2.5 hours grinding and sanding parts ready to weld and final fitting.

Started welding bits and pieces together. I left the seat mounts to last or otherwise it wound fit back in the jig.

I give my welds a C- grade as I was inconsistent with my weld quality.

My dickhead moment was when I realised my welder was set on 'lift tig' @ 100Amps for a couple of welds.

It took roughly a day to complete my chassis with many interruptions and distractions.

I found GF coping devices useful.



Lay out of parts.



Steering Post and Seat mount jigs















Ben.

I dont recall a gas torch being used on my chassis
glad to see you were paying attention, and the rotating jig worked for someone else

Nice to see Ben.
Pre heat is important as it lets the weld cool more slowly. In doing so it releases more of the trapped hydrogen that makes the weld brittle.
Some 200 degree C, pre heat, "Ferrocraft 16, low hydrogen" rods and nothing is letting go on the drill tube.
The Satincraft rods are good for all round, all position work too. They are really nice for vertical down.

These are looking fantastic and will be a great fleet when finished.

Seat's done now for the axles...

Nah it will never happen sn.

keep in mind the yacht is pointing back the way it came too!!. twas a dark and rainy night when travy set out to get a rock from the island.
i do recall his cry of "come on ya soft c##ks"
meanwhile the pods looking great john , have you finished with the jig yet so we can get it back

And 1 to the front and you have a trimaran