Changes afoot!

As we progress on line moving towards a new set of rules, I have been realizing that there is a movement afoot within the core i550 class group to limit what I feel is the best part of the i550 experience. The fun development tweaks we can all make to our boats. After a couple of months of work in private on the proposed version 3 rule set, what this core group has come up with basically makes many of the boats sailing and being built “Grandfathered Boats”, hull 130 most definitely among them. So, I figure that if we are going to have an orphaned boat, we may as well get the maximum fun out of it. To that end, I decided to go ahead and do some of the things I had been wanting to try but had hesitated because I knew that some within the class would not feel comfortable with them.

Chris Beckwith, the designer, has just announced that he was indeed doing inboard rudders for his new i550 build. This is something I was holding off on as while I really do not like transom hung rudders, I thought some within the class would feel it was an advantage. Why I worried about that with carbon masts and the like, I do not know.

Now, we an going to do it. I will be staying with the twin rudder set up and will not not bother to make them easily removable. The linkage will be above deck and two pins will be pulled, a bunch of screws removed and they will both come out, rectangular cassette style. This is the same basic set up used on the older SR trailerable models. The rudders will be the same as I was going to use, just modified a lot. It will be fun to do and an interesting exercise.

The other thing that I pulled from my experience with the SR25 (Ruckus with us, Putz originally) was the keel stepped mast. While in many ways, it complicated things, both for the construction, raising it and now it seems with the new rules, it allowed us to use the lighter section and still keep the stiffness we wanted.

The last thing we are going to try is based on the following from Glenn Henderson’s old SR line brochure:

"One prominent feature in the aft underbody at the rudder post is what we call a “reflex”. This is where the underbody going towards the stern in it’s normal upward direction is slightly reflected back down. Subtle but effective. In light air, water separates from the stern before traveling down this reflex reducing wetted surface drag. In higher speed to length ratios, this reflex flattens out the stern wave, making it form further aft. This artificially extends the waterline of the boat increasing waterline limit. In a good breeze an upwind SR appears to be planing (we have simply fooled the water into responding to what seems like a much longer boat.) This reflex also increases hydrodynamic lift enabling the boat to plane off wind like a powerboat."

From my time with our SR25 Ruckus, I can tell you the boat was as faster upwind, when we got it right, than most 30 footers. I will say though, that this was done prior to 1995 and so sportboats have progressed some since then.

I am by far not an expert in the field of boat design. I can not call up Glenn Henderson and ask him to locate and design this “reflex” but I do have some interesting information from the SR25 days and so, I am going to give this a try on the i550. It might help, it might make it worse. That is the fun of doing this stuff anyway. Will the idea work and how well?

I suppose some may consider this a manipulation of the rules, but as I have been consistently accused of doing it anyway by a few on the i550 forum, I may as well go ahead and try it. Besides, regardless of what anyone might wish to think, the ideas we are going to try are indeed well within the current rule set. More than likely others have done and will do even more, including a few of those trying to limit what we can do.

The work begins again next week, The topsides need about two days work and then we can start on the hull bottom. It will be interesting to try to figure out the “reflex” and getting the hull to do it. I am planning on using divinicel to add to the hull bottom plywood to accomplish it. Care will be taken to insure that things like freeboard and the tolerances involving the shape of the hull panels are held, perhaps even the tighter than the current +/- 1". Also, doing it this way means it can be removed if it makes the boat worse! That is one of the beauties of building your own boat this way; you know it, how it is put together and so you can also take it apart and change something if you need to.

I am putting this out there and will document how it goes so that, if possible and if it does what we hope, others can follow suit if they wish. This is what a development class, even a restricted one, is all about. Having fun and experimenting within the rules. And besides, Notorious may as well live up to her name!