Going Square Top

On the N5.2, There's a turnbuckle on the diamond wires to adjust tension; that's the adjustment that makes sense to me for a flatter sail. More tension on the diamond wires = less bendy mast. More downhaul makes sense too, but I'm already doing that.

Good luck on the surgery dmgbear55. I like the name of your boat! Very clever. I think I saw that up for sale last year, are you the new owner?

Yes, in fact I have owned the boat since 1976 then last summer I decided to do a complete rebuild. Now the boat is better than new, until I go out and mess it up.

The diamond wires control flatness by allowing/controlling the bending when the mast is rotated. The downhaul can flatten the main without rotation. So it is possible to get a cleaner airfoil. I forget what Andrew suggested for the downhaul, but likely it was in the 6:1 ratio, much more than was on the original setup.

check the portsmouth tables... off the top of my head you can/may/should take ratings adjustments for:
- non-class legal mainsail (regardless if you're class rating, it's not the sail the boat was designed for)
- non-class legal more than 5% bigger than the original sail

just do the math on original square footage of the main compared to your new sail to see which adjustment is appropriate....

on my H18 I made lots of changes and the ratings adjustments usually confounded the RC:
- non class legal main (but NOT 5% bigger) had a square top
- barely underweight (there's a sliding scale adjustment for got what it was)
- eventually I used an SX jib.. higher aspect than stock H18
- ultimately a spinnaker....

LOVE the Hobie 18 and still sail one when I can, but ultimately I went to a new platform that all these things were designed to be in harmony w/eachother from the start....opened up a whole new world of sailing. (moved to F-16 if you're wondering...)

Bottom line, do what you want and have fun. 🙂

Square tops are a tricky addition. I have been using them for about 20 years now, big multis and beach cats. If you don't let them breathe in lighter airs, they can really slow you down. I have found that if the head is too big, it loses it's efficiency. There was an earlier conversation about rake and rig balance. Someone did mention that the boards and hull add a factor, that is correct. A boardless boat will respond differently than a boarded boat. I have raced 5.0s, 5.2s, 5.8s, Tornadoes, Prindles, 6.0s and the sailplan is way different for all of them. If you add a squaretop, you need to make sure the main is cut flatter than a pin head main. The squaretop acts like a lever arm, which depowers the boat easier and keeps it incontrol more. It becomes a compromise between drag vs power & efficiency. Each sailmaker has their magical percentage of what the head length should be. This also depends on the boat. I'm currently using an old Tornado main with the head cut off. it does ok. The top is pretty flat, but it works for the boat. I've done 26.4 knots, so it isn't too bad. My 19, I had a squaretop main (sized as the MX), and a larger jib on a N6.0 foil. The amount of rake looked like a H-16... It was nuts... On the 5.2, I would add a small square top and a larger jib. I used a H-16 boom as a bow foil on my 18-2 mod. Adds good low power. The 5.2 can handle the power. The sail material makes a big difference as well. The plastics are more expensive, but they will hold their shape more consistency. But, do keep in mind that in higher wind, off the wind, the boat will power up very quickly. When you are off the wind, get a puff, and ease the main, the boat does tend to power up more.. just have to be quick on the helm and sheet.

Cheers...
Scott Tuma
Prindle 18-2 Mod
Tornado US626

I have been playing around with a variety of modified square top mains on my 1982 G-Cat 5.7. It came with original pin and a cut down Tornado "racing" main. I acquired a 18-2 "fathead" main and cut 18" off the top to fit the mast height and give it a true squaretop cut. The 18-2 is only a little bit bigger (4%) than original in square foot area but much higher aspect ratio with an almost decksweeper effect with stiff downhaul.

So now the original pin is the heavy weather (20+) sail, the Tornado is 12-20mph and the 18-2 is everything below 12mph.

In general, comparing the original pintop with the squaretops: you feel everything faster and harder and can make adjustments quicker. In light air you will get alot more power from the top of the sail than you would otherwise.

Said another way, my pintop feels soft and my squaretops feel hard, and my highest aspect squaretop feels hardest. Yes I know i just listed them in order of old to new but my 30 year old pintop is practically in new condition and is in the best condition of all 3 of my mains.

Hope this helps....

BW

RRoS and DP-N info here:
[url][/ https://www.thebeachcats.com/pictures?g2_itemId=126640url ]

Hi,

I have today just ordered a flathead from Slo for my 5.2, Carl assured me that although it will be a more powerful sail it can be depowered more than the pinhead so is actually better in windy conditions (which we get a lot of here in Western Australia) in summer).

I'd be really interested in what settings you are finding works well for this sail on the 5.2, e.g. what mast rake etc, be great if we could share some experience on using this sail on the 5.2.

Could anyone with a Slo flathead on a 5.2 please post pics of their downhaul setup? My old pintop has blocks fixed to the clew plate, so I need to figure out a new downhaul setup based on an S hook for this sail.

Super excited, now just have to wait 2 months for it to be delivered!

Anthony

I worked with Andrew at Slo and his suggestion was to try the "old" downhaul and then decide what would be needed. Being as I am way behind on my 5.2 project that answer worked for me. But I am really sure that the new sail is going to need way more downhaul tension to take advantage of the material and the shape of this sail. I think the big advantage of these sails is you can keep the mast inline with the leading edge of the main and then pull it even flatter with the increased downhaul. Next question then is the hook on the top of the mast up to the greater load, along with the little swaged bit on the wire halyard and/or the halyard itself?

I owe everyone an update on this finished 5.2 project and my hand has healed enough to go sailing, so stay tuned.

dmgbear55 wrote: I worked with Andrew at Slo and his suggestion was to try the "old" downhaul and then decide what would be needed.... Next question then is the hook on the top of the mast up to the greater load, along with the little swaged bit on the wire halyard and/or the halyard itself?

I need to replace my downhaul for the new sail as half the current downhaul blocks are on the tack plate of the old sail, it was 6:1 so I could just replace the blocks on the tack plate with a triple block and an S hook to hang from the new sail, but I was thinking about going to an 8:1 setup like this:

Its kind of hard to see in that image, but basically double block either side at the top, and a cheek block and pivot block either side at the bottom, it has the advantage that you have a downhaul line exiting out to both sides of the tramp.

The swagged halyard fitting was my next concern, I wonder if anyone has ever tried fitting something like the newer hook and loop system on a 5.2, e.g.

Of course the 5.2 has a different head without as much overhang, so might just have to try the swagged wire fitting as is and see if it slips or not.

Dave, have you got any photos or threads covering your 5.2 rebuild (I love the color of the hulls from the profile pic)? I look forward to hearing how you get on with your new sail, be great to get some shared experiences (even if only so I can live vicariously through them whilst I count the months until mine is delivered 😉 ). Did you get the laminate radial jib too? I am just going with the new main and the old jib for now. Sorry to hear about your hand, hope you are able to get back out on the water soon!

Anthony

Anthony,
Here is what "This End Up" looked like before getting the name back on the sides:

I did get both sails made by SLO.

In the technical photo albums I tried to document all of the steps I took with the rebuild. Inside that album there are three more key albums that show what I did to the aluminum parts, the fiberglass and the tools I used to get these jobs done.

I also created a bunch of video on this project and I really need to do a summary one and get it up and posted. Here is the first one in the series: https://www.youtube.com/edit?o=U&video_id=e8i7dEBBFE4

The whole thing was a kind of design build kind of project, so some of the thinking expressed in these videos changed as I worked through each of the steps. My goal all along was to show how to revive these old boats and hopefully save the next guy doing this kind of work some of my missteps.

I am going to be doing a lot thinking about the downhaul setup. I have a hard time thinking the original halyard system is up the kinds of loads created by a 6:1 or larger system when you really load it up. I even wonder if the old rollers in the masthead can take seriously increased loads, so the overall fix to increase the downhaul system needs to include them as well.

Hi Dave,

As I think I mentioned on another thread I watched all your videos and am in awe of the work you have done to give your 5.2 a new lease of life, hopefully you have been able to fixup up that cross bar clamp now and get back out on the water?

I just heard from Slo that my sail is ready to ship so should have it here in Australia in a week or two 😀

In the mean time I have been looking at downhaul options and am about to order the parts for an 8:1 (a double block either side of the clew, 3 cheek blocks and two exit blocks at base of mast). I think the halyard will handle 8:1, as I have 6:1 currently (using cheek blocks on clew plate so need new system for new sail), that said I probably have not loaded the 6:1 to its full extent but the previous owner replaced the hook at the top of the mast with a handmade welded up version so maybe the clue is there that the factory hook wasn't up to the load he used on the 6:1, so that maybe an area for you to watch.

Just wondering what ratio downhaul you have tried so far on This End Up, and also did you find you needed more rake by a hole or two, or more spreader rake?

Anthony

Edited by aquaaddict on Aug 11, 2017 - 01:21 PM.

In the mean time I have been looking at downhaul options and am about to order the parts for an 8:1 (a double block either side of the clew, 3 cheek blocks and two exit blocks at base of mast)

Anthony, I think i have all those parts, all Harken. I can put them on our airplane,(From Vancouver-Sydney).
If you are interested, send me your email via a PM, i'll send you photos.

Anthony I haven't changed my downhaul setup yet. The 3:1 was able to pull the sail flat, but not much more than that. I have to believe that your existing 6:1 would be adequate and if you didn't fail the hardware on the top of the mast then so much the better. This new sail is pretty flat in the first place compared to the old dacron sails, so once you are able to induce some mast bend with the downhaul I would think you are there. Overdoing it seems like a way to cause more work and complexity than is necessary. So like Andrew suggested, try your existing setup before changing anything.

I did complete the repair on two of the lugs and got everything painted again. Now I just wish I had dug out the lugs in all of the other positions last year when it would have been easy to do. There is no doubt in my mind that the sharp edges on those lugs contributes mightily to this kind of failure. Just adding more fiberglass like I did a year ago may postpone the failure, but wouldn't completely eliminate them.