IMOCA 60 Macif

I am building a new boat, form the experiences learnt from the last 2 , Rock all Night( VOR 65) and Safran, IMOCA 60.

The Macif and Banque Populaire etc are actual sister ships o the Safran, but with refinements. My new boat will have the keel nd mast move aft, to make the boat more controllable at extreme winds.

My Safran, built 3 years ago, planes easily; but it is too beamy, and going up wind it tends to go sideways.

The RAN (VOR 65) has too much weight and mast forward, making sailing downwind at extreme wind speeds very touchy. But it s a great upwind boat.

So the new boat will take advantage of both.

Your three dimensional drawings look very beautiful
and the fact that you have the experience makes it very intriguing.

What are the dimensions of your new model?

Are you going to share your plans with the forum?

Best wishes for your new project

Looks good and I really like your kingplank 50’ design - seems to work really well on the sea. I found too many open60 are a bit too low down on the water - granted they’re not very high in full size anyway but they look ok compared to the model ones which are too ‘model like’ and I think it should be possible to have the same look as their big brothers. similar to your 50’ which looks right. can’t wait to see some of your pics of the built - always good and inspiring.

I’m trying my buidling skills on a IOM at the moment to learn as much as possible before I build the IOM I will race - won’t be a bad boat I think but I know now I can build better on my second one.

Happy new year !

Thank you for your interest in my boat.
This is also a 50"boat, same length as a Marblehead.

If you a IMOCA boat down to model size, it will displace so it that you cannot possibly build it.
So you have to “cheat” by adding more volume at the belly. The smaller the boat, the more you have to “cheat”

I have added just enough so the boat will displace 4.3kg. By using an IOM size bulb and long keel, the boat is light and with a lot of righting moment, good for planning.

I had a lot of work done on the weekend , and here are some pictures of the work in progress.

From my past experience, the keel box; the very first item to be built, must be extremely strong because the fin will do its best to rip the fin box apart. Do no rely on adhesive alone; use stainless steel bolts, 4-40 or 3mm.
2 coats of epoxy on the inside before glue and bolt together. Drill all matching holes first.

When the frames are bolted to the plywood jig, check straightness. Redrill and re-align frames if necessary.

Not the trimmed down boat shaped plywood jig. It is necessary because this boat is highly chamfered on the top side edges; it may be necessary to use saran wrap to press down on the fiberglass or carbon fiber\

I hope this info will help someone to build this type of boat in the future


Indeed I will be following your build carefully as my next IOM has the latest trends in design ie a tumblehome similar to your IMOCA so the deck level is narrower and the stat of such shape is more challenging then a traditional shape. Thank you so much for sharing your build


latest built pictures

Keep up the good work.
It really looks great.

I was not going to use carbon, but a quick check in my shop I found a piece that is just right size for the boat.

fortunately my set up is suitable for carbon, and it was 4.5 hours of very difficult work to get the carbon to behave. It had a hard time going around the double chimes on the side. Seran warp is difficult to apply with one person, but I did it.
Do not recommend laying up carbon if you are not used to it.

Saran wrap? I have seen the use of peel ply for absorption or latex for smoothening. First time I see this. Can you please elaborate on your technique?

BTW, IMOCA/VOR was my first love that brought me in this hobby. But I still have to build one of these as I have never seen a design that seem to behave properly. I had follow your previous built with great interest. This one seem even more promissing. Thank you for sharing this with us.

Saran wrap is very similar to the material used for vacuum forming.No adhesive will stick to it.
Wrap you boat just like you would with leftover chicken.

5 coats of epoxy inclunding the lay up layer. Dry sand between coats with 3M no-load sandpaper(no other will work).
Hopefully that is the the final coat(shinny) ,. Rough review of the final outcome.
Dry sanding will let you know if you have sanded thru

OK for the chicken wraping! But then do you pass a roler or something on it?

You could use your fingers and gently roll/massage the pockets of air or epoxy towards the edges and discharg. Dont have to worry if you didnt do a perfect job or if the warp is puckered. You can easilt sand the excess epoxy off after.

Saran warp is not necessary on a typical IOM or Marblehead, but on a vintage Fife yacht I used it on 2 or 3 local places only, like the sharp edge of the bow and edges of the keel.

Latest pictures, pulled from the jig.

very angry looking boat; not pretty at all.

Nasty job sanding down the excess carbon. Skin irritant.

Fiberglassed the inside, nasty job, but necessary

Installed stainless rudder thbes.

Fitting recycled fin. Not that happy with it, will build new fin and re-use existing bulb

Just to concur with other posters, a fabulous build yet again - I’m in awe of both your design & building skills.

Out of interest what layup schedule do you use for sealing & strengthening the hull and do you think the hull could be any lighter if you used the planked hull as a plug & took a carbon molding?

Looking forward to seeing how this all progresses & especially to seeing how she performs on the water!!



Thanks for the encouragement and compliments Twister.
I learnt a lot from the big scale plane builders, where they use a lot of balsa and fiberglass, and very little carbon is used.
For any given hull plate, the stiffiest and lightest is a composite construction with a light and a thick core. The 2 cover material could be fiberglass or carbon. My first 2 Open boats were built with 2 layers of 1.4oz fiberglass and they were totally adaquate for the job.
I only use carbon strictly because of the coolness factor, but it does add a lot of weight, 5.6 oz vs 2 layers of 1.4oz fibeglass. I had used the mold and plug method once, and I had to use 2 layers of carbon , resulting in a very heavy and flexy structure (without the core material). But the idea really failed because to stiffen it up it was very difficut to install frames later and no adhesive will stick reliably to the hull that was waxed.
So this takes us back to the big plane boys, low tech balsa and thin layer(s) of fiberglass. Planking wood strips gaves you the most precise hull, and I always admire the workmanship of those those cedar strip kayaks

Love it! Looking foreward to follow your progress…


Modify existing fin from the Safran, found no defects, stress test OK

I’ve been working hard to finish this boat

Feel free to ask question on design and build