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PostPosted: Thu Sep 06, 2018 10:39 am 
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Location: Colorado
try a search on "small sailing trimaran" or something like that. Lots of designs come up. I cant say for sure but I would bet that none of them are even remotely as successful as the Hobie Adventures even though no doubt some are faster. But so is an old Hobie 14 along with pretty much every cat Hobie has every sold. FYI, try comparing raising the mast on just about every one of the faster cats compared to the TI mast.. TI mast setup is so much easier. Of compare the mast raising to any of the same size or larger Tri's..

I like the boat as is with some minor tweaks but its not the only sailing boat I have. Another idea that I likely will never try but I find somewhat interesting.

Instead of the floppy mast and furling sail (which I actually really really like on this boat), how about a bendy carbon fiber rotating wing mast with about a 8 to 12 inch cord. Attached to the carbon fiber wing mast would be a fat head soft sail. Maybe total sail area of 5 to 7 sq meters. You would have both a sheet for the soft sail plus a "sheet" or rotation control for the CF wing mast.

Wing mast have to be rigid to support the pressure differences they can generate without distorting so you really cant do this with soft double surface sails (been tried over the years.. doesnt really do much). Might be stayed or maybe not. In higher winds, you could probably just sail the boat on the mast alone. But.. this would snowball and you would be wondering what speed improvement you would get if the whole boat was carbon fiber and much lighter.

One question.. what makes you think a wider tail end would make the TI plane? Just making the back end wider does not resemble at all any traditional planning hulls. I think the chances are just as good that it would just slow you down from higher wetted surface. Are there any examples of existing trimarans that have some sort of wide back end?


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PostPosted: Sun Sep 09, 2018 10:40 pm 
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Location: Cleveland, OH
A hull that's fast in light air / displacement conditions AND high speed planing tends to have a deep v forward and a flat run aft. They need not be wide, just flat. Long, skinny hulls have problems planing because they don't have enough wetted surface to weight ratio- but long skinny surfboards don't have that problem. If you make the TI much lighter, it already has the deep vee forward. A much flatter run aft would encourage surfing at least, if not outright planing, esp. with the body weight aft as it is on a TI.


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PostPosted: Thu Oct 18, 2018 10:34 am 
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I understand the desire for a more robust off-shore version. But how much of the market does that represent for the TI?

I'm very new to this - just got my TI in August. For me I'm looking for a third improvements - better low wind performance, better up-wind performance, easier ability to hike out especially from the back seat. I think these all can be accomplished with a jib (preferably a simple self tacking one with minimal extra lines), and Hakas.

Oh yeah I almost forgot - fix the front hatch so it's actually water tight. I haven't gotten into anything the rough and I still need to drain the boat after every outing.


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PostPosted: Thu Oct 18, 2018 11:46 am 
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Location: Sarasota,Key West FL
Even with my planing hull mod, the boat isn’t really planing I suspect, It’s semi-planing. The problem I had prior to adding the planing mod was the pointed stern sinking down underwater at around 9mph cruise speed, going any faster required huge horspower requirements which increased exponentially, (like a brick wall).
The planing hull mod delayed the stern wave from forming and moved the stern wave behind the boat about 2-3ft, (vs right over the stern previously). This allowed the boat to get up over 15mph (with the stock motors, 20mph with modified motors, (or in higher winds with the big spin deployed). Anything over 10-12mph cruise speed gets quite dangerous, and not really recommended.
The hull speed is around 8.5mph for the TI, I don’t recommend going much over that. Running the boat fast in anything other than flat water is not recommended, ( the hull can’t withstand the stress).
Cruising anything over around 9mph is an exhausting experience even in low 5-6mph winds and flat water. If adding outboards and massive sails don’t set your goals too high, ( you will be disapointed).
Also keep in mind if your sailing upwind in say 12mph winds at 12mph forward speed, thats around 25mph winds on your face, and on your sails and masts, we snapped several masts doin that kind of crap, (really hard on the boat).
99% of the TI owners like the stock boat as it comes from the factory, majority rules, if you want more, get somethin else.
Just my opinions
FE


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PostPosted: Thu Oct 18, 2018 7:50 pm 
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fusioneng wrote:
with my planing hull mod, the boat isn’t really planing I suspect, It’s semi-planing. The problem I had prior to adding the planing mod was the pointed stern sinking down underwater at around 9mph cruise speed, going any faster required huge horspower requirements which increased exponentially, (like a brick wall).

Here is a video eventually showing stern squat at higher speeds if you don't have a clean release stern. I experience this when surfing a kayak with bow stuck inelegantly up in the air. Semi displacement tricks are becoming more of a science - another trick to overcome the hull speed limit is upward lift, such as from your wing jib.


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PostPosted: Thu Oct 18, 2018 8:57 pm 
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That’s really interesting, it pretty much shows exactly what happens in real life. In my case it was just dumb luck, I accidentally designed something that actually worked, lol.
Same with the 2ft bow sprit, just a wild idea at the time on a whim, by angling the foresails, the sails also create tremendous lift to the bow. With my big 135 sq ft spinnaker deployed running downwind in 20mph plus winds the bow is a good 12-18” inches out of the water, and with the planing mod installed only the rear 1/4 of the boat is in the water, ( actually gliding on top of the water. Without the bow sprit there is great risk of pitchpole, (because the TI sits so low in the water, lol I’ve pitchpoled 6 times at high speeds, very painful. Just guessing around 1/4 of the sail force is lift when pushing the boat hard due to the slanted foresails.
FE


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PostPosted: Sun Nov 04, 2018 5:11 pm 
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fusioneng wrote:
Same with the 2ft bow sprit, just a wild idea at the time on a whim, by angling the foresails, the sails also create tremendous lift to the bow.

I saw a simpleton way to shove the jib forward (and shape it without your ram air inflation) on a little Russian sailboat. In principle it looks like the iceboat depicted below, where the jib-boom extends forward of the pivot. But it doesn't get that saggy as the forestay goes slack, because it is a full lanteen rigged jib - self tacking and self vanging!

They just hooked the head of the sail to the top of mast, and put a short leash from the jib club to the bow. When the mainsail pushes the jib down, none of that misshapes the jib (which has 2 light spars, the bottom being loose footed) because it is all taken by that leash being pushed to leeward. Net result is a perfect shaped jib with an especially forward position. Oh, I guess it gives less lift on downwind.

Image

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PostPosted: Sun Nov 04, 2018 6:34 pm 
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That’s a brilliant design and I think would really work well on a TI, (believe me I tried a gazzilian different designs), never thought of that one though.
You could probably use any jib typically designed for cats or lasers, ( which never work worth a crap on TI’s because of the floppy mast). And just add a pole at the base, (you would need an extra tension adjustment on the pole). You wouldn’t hinge it in the center though, (about 1/3 from the front would be your hinge point), this way you can control it from the back, (just like a regular jib, (I had two control lines on earlier jib designs, one for each tack, ( poor mans self tacker).
You could get away with a much bigger jib/genoa.
I really like the idea, I actually think it would work very well.
Just my opinion, after first look, would still take a lot of development to get it right, but being able to work directly with common jibs (from other boats), would cut design time way down, way easier than having to invent new stuff and concepts from scratch, lol
FE


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PostPosted: Thu Nov 08, 2018 8:15 pm 
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Agree,

That jib setup looks impressive (as does the whole ice boat).

Love to see a few more photos of the ice boats bow and control lines.

Big fan of self tacking and self vanging design.....keep it simple.....

Be interested to see how this rig would help the pointing ability of the TI (anything would help!). Impact on rudder control is also of interest.

Jim

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Hobie TI 2016
Hobie AI 2015 - sold
Hobie Rev 13 2014
Hobie Outback - 2008 - sold


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PostPosted: Fri Nov 09, 2018 2:36 pm 
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I can't remember the class name of that iceboat, which is the key to googling up photos of the rig. I bet it had one jibsheet going down to a center anchor just ahead of the mast. It was mentioned in http://forum.woodenboat.com/index.php but when I search there for self vanging and jib or whatever there are too many posts to sort thru. Todd Bradshaw, a recognized guru of sail design, was involved in the discussion. Almost all of his 10k posts over the last 20 years there are gems of insight, whether it be self tacking or other.

The Russian sailboat I saw also had a thin vertical spar like on a Sunfish. I'm not sure that is helpful, but it led to a straight forward edge instead of the concave one on that iceboat. It looked very aerodynamic, kind of like you moved a Sunfish sail forward of the mast. It didn't have that annoying imprint on one side of the sail from a mast or forestay like most lanteens, since there was no forestay.

Image

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PostPosted: Fri Nov 09, 2018 3:34 pm 
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Location: Pennsylvania - Philly Area
yes,

I was thinking the same....lanteen rig with solid spar similar to the sunfish (which I have sailed for many years) main sail but placed forward as a jib...

Like the way the bottom spar of the lanteen rig is attached to the extended bowsprit....wonder if something similar could be designed for the 2019 Hobie Tandem Offshore... ;-)

Jim

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Hobie TI 2016
Hobie AI 2015 - sold
Hobie Rev 13 2014
Hobie Outback - 2008 - sold


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