i550class.org

Firstly for those of you with carbon masts what are the differences between the masts from C-Tech and CCI
And secondly how did you build your mast support/step and do you have diagrams for how you did it?
I’ll be building an wide cockpit no cabin boat with a carbon mast.

I will do two posts: this one is about the masts.

The C-tech masts are round with an applied luff groove, like many skiff and sport-boat masts. I believe the C-Tech mast is wound over a mandrel and autoclave cured. It is shipped in three pieces and the owner assembles it.

I have the first, and possibly only CCI mast so far and have not yet sailed with it. This summer, COVID 19 willing .... The section is not round (see second photo) and the luff groove is applied like the C-Tech mast. The mast is built in female tooling, vacuum bagged with an inside bladder and cured in an autoclave. The CCI autoclave isn't long enough for a whole mast so CCI moulded it in two sections, but did the assembly before delivery. I don't think they trusted me. I also show a picture of my boom in half of its its tooling.

Oh, another picture of the mast when I was fitting spreader cores before putting carbon fibre to them.

How did I support the mast step?

I used a Dwyer mast step. It was easier to buy it than make one, especially at the reasonable price ($50 or $60US?). To support it I built support structure into frame 89.5 (I think that's the one). See the frame photo and the near complete boat photo, in the rotisserie.

A recent Russian build used a simpler solution. Like me, he wasn't going to sleep on an 18 ft boat so he simply put a full bulkhead at that station. He also made use of a Rhino to loft additional frames for the boat to simplify building a 'true' hull. For a spinnaker recovery system you would have to add a tube and 'mouth' in the foredeck and forward compartment. Probably simpler than my approach, and lighter too.

Warren, good description, very accurate with re: the C-Tech

Werner, I have a C-Tech mast (and boom and prod) and the mast came, from C-Tech, with a SS mast plate. I have a picture of it somewhere, but my laptop died two days ago and I am still in recovery mode.

The only thing I did to make things fit appropriately is build a flat landing pad for the metal mast plate, which I simply screwed into the pad with self-tapping SS screws (if I remember correctly, which is admittedly, rare these days). Again, I have photos and there are a few low-res ones on my build-log,
http://www.nbayracing.com/i550Build.htm

Thanks so much Warren, you’ve been a wealth of information, I hope you won’t mind me picking your brain further as I progress with my build once the Covid-19 dies down. Like you I’m also going to be building a “sports model” boat I won’t be sleeping on. I’m very impressed with the boat built in Australia by Chris Lee (the pink one) but haven’t been able to get more info on it.
Just so that I understand correctly as the plans are vague, the mast support is just a compression structure to support the top deck and then the mast step sits on top of the deck over the support?

admin wrote:Warren, good description, very accurate with re: the C-Tech

Werner, I have a C-Tech mast (and boom and prod) and the mast came, from C-Tech, with a SS mast plate. I have a picture of it somewhere, but my laptop died two days ago and I am still in recovery mode.

The only thing I did to make things fit appropriately is build a flat landing pad for the metal mast plate, which I simply screwed into the pad with self-tapping SS screws (if I remember correctly, which is admittedly, rare these days). Again, I have photos and there are a few low-res ones on my build-log,
http://www.nbayracing.com/i550Build.htm

Thanks for the info, I had a look at the log and it illustrates the mast step attachment quite nicely

Werner, yes, the mast support is in its simplest case just a compression post, but look at what people have done. One early builder had a (buckling?) failure of his compression post which brought the rig down and destroyed his cabin top. So don't skimp. The Russian full bulkhead is a light and robust solution for an open boat. You can then access the bow compartment with a deck hatch like the Melges 20.

Lee's build log ( the fellow that drew the plans) on this site has a full bulkhead as I recall (and a longer cockpit).