Formula 40 singlehanded trimaran build log

Hi Jeff, thanks for your comments I thought long and hard about the design choice. What impressed me about Kurt's boat is that it had really good light air performance. This has been independently confirmed by it's performance against other trimarans in club racing in Puget Sound. Spirit of Emu for example is similar in dimension but weighed about 3 tonne it was very sticky in the light and apart from a few outstanding performances was not very competitive (their best I think was doing the Melbourne to Geelong passage race in under an hour and a half, really fast but ideal conditions). From my experience of club racing light air performance is critical the boats that can maintain good averages win races with top speed being of less importance.

Looking at the second hand market most of what is out there requires extensive refit is focused on cruising or is very expensive to purchase.

The other thing that I considered is that most designs that are available are cruiser/racers which while nice aren't what I'm looking for. Having a custom design drawn (was around the 30k+AUD mark for a design from Tim C or Tony G. I didn't price a custom design from Kurt Hughes so his design/engineering fee may be less) versus the 3kAUD price of Kurt's stock plan there is 27k in real terms that can be spent on materials. My view is I'll consider the boat as a write off in terms of resale value if I get anything for it when I'm finished with it I'm happy it's a selfish pleasure to own a boat that is just focused on racing and I cant expect much back. If the cost can be contained I can view it and justify it like purchasing a luxury car that will depreciate quickly.

I wanted a boat that was demountable and able to be containerized, had a moderate rig and was able to be singlehanded or shorthanded with gear that wasn't too heavy Kurt's F40 design ticks the boxes. It's not just the cylinder mold process but how he looks at the complete construction process that adds up to savings. I could ask him to rescantle the boat for foam core but once again it's another expense. If I stick to his stock design it means I pitch less money into the project that I'm not likely to recoup.

Due to the boats demountable nature If I choose to build foam sandwich or carbon floats or main hull in future I can build them and bolt them on.

 

Yeah i agree with Jeff... the only way i can save money using plywood is to use the NON marine grade stuff - no okume or anything like that, as the cost of the marine grades of ply actually exceeds the cost of foam...

Just for your reference, the price of 15mm foam per sheet is $140 - thinner is cheaper.
epoxy resin is $2400 per 225kg drum,
56kg of hardener to suit is ~$600
stitched e-glass fabrics are ~$6 per m2.

Cost of a 2400mm x 1200mm x 15mm foam sandwhich panel with 600gsm e-glass/epoxy laminates is $260 via wet layup, or $280 via infusion. Weight = 12-11kg respectively.

Marine ply costs over $100 per sheet, then add epoxy and sheathing etc. If the design requires multiple thin ply sheets to build up the required hull thickness, the cost is higher again. Ends up very little difference in total cost to build. But the resale difference is huge...

 

Did you get a definite quote from Kurt re the 30k ? Sounds a bit high.

He's quoting about 34 k for a 79 footer cruiser.

Whats your attitude towards a new custom design at full designs rates. Who owns the design. Can the designer then sell them as stock plans in his port folio.

OC

 

OC I'm not sure on that front the detail would vary depending on the purchase contract.

I didn't get a quote from Kurt I was satisfied with his stock plan the 30k+ approx figure is a custom trimaran design from Tony G or Tim C.

As noted groper not concerned about resale value a racing trimaran with low payload capacity is not worth much that's why it's important to keep the cost down. It's a selfish project for me that I don't expect any return on. Resale price is not good for any racing trimaran larger than a trailerable type and even they are hardly setting the world on fire at the moment eg The 28' racing trimaran ATL Composites/Riverside Oaks has sat on the market at $29,500 for a long time. Bargain buying if you want a small race tri.

 

The cylinder molding looks pretty cool, I first saw Kurts vid was in mid? 90s, a customer had it, I'd been repairing an old ply daydream for him & here he come with Kurts catalogue & video, sat down & watched..... looked like yippee kye aye boatbuilding(in a good way) compared to what was "usual", the vid was great with Kurts commentry, pretty honest stuff. I've only heard of one Aussie built cylinder mold boat about 28' built maybe in WA.
Interesting you cite Riverside oaks as a sweet deal, when Rob Denny was repping for Adhesive Technologies it was like the first thing that we heard about with Duracore?, I've wondered how it's held up over the years.
Jeff

 

From all reports Riverside Oaks has held up well. I was chatting to a few of the guys who have been racing up North who had looked over the boat and were quite impressed. It's demountable of course not folding which drops it's appeal a bit to some but still very competitive on the race course.

I've read that the GeForce catamarans are built in strip durakore by Julian Griffiths at Noosa Marine so the general feedback over time for it as a building material must have been quite positive.

 

May I respectfully suggest you alter your orginal posting so its not interpreted that is what Kurt charges for a 40 footer with
minimal interior design work. Perhaps should have read, Having a custom design drawn was around the 30k+AUD mark from Tony G or Tim C , particularly after quoting Kurts name in the same sentence.

OC

 

I can see that it could cause some confusion so edited it to the text below.

Having a custom design drawn (was around the 30k+AUD mark for a design from Tim C or Tony G. I didn't price a custom design from Kurt Hughes so his design/engineering fee may be less) versus the 3kAUD price of Kurt's stock plan there is 27k in real terms that can be spent on materials.

 

Thanks.

OC

 

Whats Payload Capacity any body.

I can't find the thread where this was thrashed openly and no body got a real answer just many different answers.

So asked a expert :

What's the payload figure.

Heres

Kurts Interpretations.

December 7, 2013 at 8:32 pm
what’s your definition on ?

Weight.

[ Bare boat, including engine, propulsion, mast, winches sails, anchor and chain, sheets, water and fuel tanks but empty, radios, electronics instruments, gen set. life raft, safety equipment ] ?

Displacement weight.

[ Added weight. = Crew, water, fuel, stores, spares, parachute anchor and rode, inflatable and engine ... ]

December 9, 2013 at 5:07 pm Kurts reply.

I call weight complete vessel, empty and dry. I can’t think of anyt other definition.


My question to Kurt in reply.
December 10, 2013 at 6:30 pm

Whats does a complete vessel empty and dry mean?

There has been a lot of complaints on world websites by posters prospectus buyers that they can’t get strait answers from designers and they all have different definitions.

Some say it is done on purpose so if the boat does not float to design lines they have some degree to scrurm explanations and exonerate themselves.

Terms used.

Weight.

Displacement Weight.

Payload Weight.


Kurt says:
December 10, 2013 at 7:34 pm
I have no idea what other designers do.
I thought I gave a “strait” answer on this already. Complete, empty and dry.




December 12, 2013 at 5:44 pm
Thanks

I’ll add my question and your answer to the forum debate re your interpretation with your name.




OC

 

Be interested to know the mainhull max beam and sole beam.

Plus the wetted area and the sinkage factor kg/cm

Read the article and got the impression re narrower beam, with water ballast to compensate for the flying windward hull.

He did not elaborate where the inlet skin fitting would be placed, I assume the main hull to obtain the water needed or how it was dumped or pumped across to the other hull during or after a tack. Would have to be a pretty good suction pump to get 300 kilos water on board during and after a tack. Just talked about 300 kilos less weight in beam and compensated with 300 kilos water ballast.

Do any of the modern trimarans multihulls apart from Hydroptere use water ballast. If they don't then it's still maximum square beam.

Sounds like Vodafone suffered the same problem and will only get worse with age or ocean sailing and encountering rough seas. One would think rather than hoving to they would devise a system to deploy a parachute anchor and save delamination damage or even a complete section parting.

What about Team Australia ? Same age build?

OC

 

lock Crowther was diametrically opposed to using water ballast in the upwind hull, as it still had to be carried by the lee hull and thus caused more drag. By adding to the overall displacement.

 

I'll have a look at the plans if I get a chance when I'm in the workshop tomorrow the hulls are mighty skinny and cramped that's for sure. I never enquired re wetted surface or sinkage.

The water ballast idea that Nigel was discussing in the article seemed to be more conjectural than something that was ever put into play. The large trimarans normally have water ballast tanks in their main hull now. Hydroptere picks up it's water ballast through a fitting on the rudder. I'm not sure how they transfer the ballast (I think Doug posted up something about that but cant seem to find it) but they do have a diesel engine onboard so it may be pumped. The Gougeon's catamaran "Strings" uses a reversed dinghy bailer to fill their ballast tank ultra simple and lightweight.

Square L/B seems to only be preferred in Multi50's now the larger trimarans including the MOD70's are all undersquare.

It's a shame the ORMA class never really recovered from the 2002 Route du Rhum most of the boats were recovered and repaired but that really put an end to it. The MOD70's were a response to the demise of the ORMA but now we have had two capsizes within a short timeframe and some of the sponsors like Foncia withdrawing sponsorship and leaving the class close to failure. Hope there is a future for them as I've enjoyed their racing so far.

just checked the measurement 1040mm at the waterline at the main hulls drawn waterline and it's about 1120mm at it's widest point. There is no sole except in the cockpit you stand on the bottom of the main hull it has about a 12 to 1 fineness ratio.

 

Is not Kurts 40 footer racer - your build 39ft... x 39 ft... which is a square L/B. Main hull beam then is just under 4 ft.

Funny how they reduced the beam ratio on the Mod 70 from the ORMA and the 70's are Capsizing. Any connection. Probably will be with another 3 capsizes.

The payload on the kurts 40 footer would probably mean dingy / rubber duckie - motor is left on the moorings once you add all the safety equipement for racing regs.

OC.

 

The F40's were just a whisker under 40' so they could be containerized. Kurts design is 39'11 x 39'9 close enough to 40'.

When they were designing the MOD70's VPLP stated that they wanted to reduce the tendency to pitchpole which they seem to have done as the capsizes have been leewards capsizes instead. I'm not sure which is preferable you can sometimes recover from a nosedive/pitchpole but a leewards capsize if not checked will definitely see you over. The Spindrift capsize appeared sudden but the Virbac Paprec capsize looked like it could have been prevented.

Yes, payload is a challenge we have to carry auxiliary power and some fuel but it will just be a longshaft outboard on a beam bracket realistically I envisage needing the help of a RIB or two when docking or to get back on a mooring if it's windy and we are in race trim we will probably run a more powerful outboard for day sailing/racing and payload allowance is not critical.