perfect size of genoa sail when using roller furling at open sea sailing

Previous Topic Next Topic
 
classic Classic list List threaded Threaded
8 messages Options
Reply | Threaded
Open this post in threaded view
|

perfect size of genoa sail when using roller furling at open sea sailing

hardbob
Dear fellow SeaHawk sailors. I am getting pieces together to upgrade my SeaHawk with a Nemo Wonderfurl (roller furling gear) and is looking for advice on a few issues that are somewhat related.

The first thing is what size Genoa sail I should go for. I intend to have one tailored for me by a sailmaker. The discussion I found in the forum on this conclude that more than 130% genoa is not very useful and potentially something that could put the boat out of balance. Does anyone with experiense sailing at open sea with roller furling agree with this? Does anyone think I should go for less?

Next, what are actually the dimensions of a 130% genoa for the fractional rig on a Seahawk? I have seen the diagrams on the site, but I cannot read the numbers. My boat Totte is a crossover model with both Redcraft and More and sons features. She looks very similar to H100 currently on the frontpage of the Seahawk site and the mast is the SSS version (aluminium color).

Also, I am wondering if it would be a good idea to add a new attachment point for the forstay 10 cm further up the mast to ensure a suitable angle from the internal halyard block in the mast. The conventional way is to add an external halyardblock 16.5 cm below the eye where the forstay is attached (please see the attached figure). My motivation for this is partly that it would allow for a sail with slighly more luff and I think I would be able to fit in the full size of my furling gear without having to make any modifications to it. The full lenght of this gear equeals a forstay that is 460 cm. However, from other discussion in the forum, I guess the conventional way is the safe choice (i.e. adding a halyard block 16.5 cm below the attachment point for the forstay and reduce the lenghth of the roller furling gear to the standard lenght of the forstay (does anyone know what that length is?)

Finally, I am looking for a suitable fitting for my kicking strap that fits with the keyhole on the boom. I am not sure what the original piece looks like and currently I am using something homebuild that is starting to rust... Do you know what it is I should be looking for and where I can order this?

Many thanks for any advice. And as always, applaus to Greg for building such a great site

halyard block figure
Nemo Wonderfurl furling gear
Reply | Threaded
Open this post in threaded view
|

Re: perfect size of genoa sail when using roller furling at open sea sailing

brian johnson
Hi there.
We sail our Seahawk on the open sea with roller furling jib.  In winds over Force 3 we use the normal small jib but in light winds we use the original Genoa which looks around 120%.  I wouldn't go much larger than that because things could get a bit lively in strong gusts.  Having said that, with roller furling it is easy to reduce the sail area but you lose the shape very quickly.  

I can't see why you should not attach the forestay further up the mast to make use of the full length o your furler.  That would also give you a better angle for the halyard attachment.

The kicking strap attachment is easy to fabricate by welding a ground down stainless bolt to a stainless strap.  The bolt head is ground to fit into the boom fitting.  The strap needs a 30 degree bend to line up with the angle of the strap.  I did this on my previous boat using a friend's MIG welder with stainless wire feed.  I can't get to my boat at the moment as it is stored in a barn behind a couple of caravans, otherwise I would get a pic for you!

Hope this helps   Brian
Reply | Threaded
Open this post in threaded view
|

Re: perfect size of genoa sail when using roller furling at open sea sailing

GregSeaHawk
Administrator
In reply to this post by hardbob
Hi Thomas,
hardbob wrote
Next, what are actually the dimensions of a 130% genoa for the fractional rig on a Seahawk? I have seen the diagrams on the site, but I cannot read the numbers. My boat Totte is a crossover model with both Redcraft and More and sons features. She looks very similar to H100 currently on the frontpage of the Seahawk site and the mast is the SSS version (aluminium color).
I bow to Brian's knowledge of what works best at sea. As a Broads sailor I find a genoa largely useless. Constant tacking makes anything that needs dragging past the mast on each tack means you never get the sail set before it's time to come about again. And meandering rivers mean you rarely stay on a tack for more than 30 seconds.

However, to solve your problems with reading numbers, I have just re-scanned the Larger Rig image which should make reading the numbers much easier. In case you're not familiar with the technique on a desk/laptop do a right-click over the image and find an option such as "View Image" or "Save Image", which should allow you to zoom in to see it at its new higher resolution. My belief is that the drawing is reasonably accurate. The scale is marked on it and there are a number of known dimensions from which to do calculations.

H100 is Sea Holly and if you use the search box you'll find a little further information about her. She's one of the few boats with a known age (and original price) and a little older than Totte.
Greg Chapman
GregAfloat - My Boating Biography
Reply | Threaded
Open this post in threaded view
|

Re: perfect size of genoa sail when using roller furling at open sea sailing

hardbob
Many thanks Brian and Greg for your replies. The new "taller rig" diagram is much easier to read. However, I still had a hard time figuring out what numbers indicated what measures. For instance, the forstay has one number (14.50 feet) which could mean the entire length of the forstay, the luff of the standard jib, or the luff of the standard and large genoa on the existing rig. My impression is that it is the latter. From my print on A4 paper, I then get a conversion factor of 28,2 and not 32 as indicated for the original. For other measures, I ended up with slightly different conversion factors, but all in the range from 28 to 29. Assuming it is the genoa luff that is 14.50 feet (442 cm), then I get from the diagram that the standard forstay measures 522 cm. When measuring the length of my actual forstay + turnbuckle, I end up with a measure of at least 506 cm (turnbuckle at most compact position and with the mast down). I guess reality is somewhere between 506 and 522. The standard mast, I measure from the diagram to 606 cm vs. 613 cm when measuring my actual mast (hence, I do not have the taller 24 feet mast).

Regarding the numbers on this diagram referred in the section "boat/full description/sails" I noted what I think is a mistake. The following text describes the existing rig: "...the existing rig in dotted outline. These consist of a standard and large main at 89.5sq ft and 103.7sq ft and a jib, genoa and large genoa at 36.5sq ft, 49sq ft and 104sq ft." However, I think the number for the large main on the diagram reads 108.7 sq ft and it refers to the larger main sail with the 24 feet mast. Also, the diagram does show a large genoa for the existing rig, but the number 104 sq ft does not match that sail from eyeballing it up against the standard genoa. I think this number is for one of the genoas displayed for the 24 feet mast.

My own sails are different from any of the sails on the diagram.

My jib measures (luff/leech/foot): 390/353/145 cm
My mainsail measures: 450/??/225

Reading your replies and the details on the site, I think the standard genoa will be the sail size I go for my furling gear. And my impression is that this has a luff of 14.50 feet and a foot of 8 feet and 6 inches, and gives an area of 49 sq feet.

Many thanks :-)

Reply | Threaded
Open this post in threaded view
|

Re: perfect size of genoa sail when using roller furling at open sea sailing

hardbob
In reply to this post by brian johnson
Hi Brian. Thank you for your time and wisdom :-)

When using the standard genoa, is your sail then on the inside or the outside of the side-shrouds? And can you still use the Reedcraft positioned jam cleats on the sides of the cabin door? Or is something further aft required? And where are you securing the rope that controls the furling of the sail?

Best regards, Thomas
Reply | Threaded
Open this post in threaded view
|

Re: perfect size of genoa sail when using roller furling at open sea sailing

brian johnson
Hi Thomas

Genoa is outside the shrouds on a run but I sometimes have it inside when beating into the wind.  there are two set of eyes on the cabin top through which the sheets run.  The aft set are for the genoa.  I have jamming cleats on the cockpit coaming - my boat has never had cleats on the cabin bulkhead.  That brings the sheets nicely aft right next to the helm so makes things easy when single handed.  The furling line is led aft through a number of eyes to a jamming cleat on the coaming, again next to the helm so easy to furl.  The boat is in a barn atm under a truck tarp with mast down so not easy to take photos.  

Hope this helps

Brian
Reply | Threaded
Open this post in threaded view
|

Re: perfect size of genoa sail when using roller furling at open sea sailing

GregSeaHawk
Administrator
In reply to this post by hardbob
Hi Thomas,

My boat, Just 17, had the standard Reedcraft set of cabin top and fairleads, so sounds more like yours than Brian's. When I bought her I was presented with a genoa from another boat. It's luff was over sized but its foot was a perfect length (never measured it!).

Just 17's Genoa
As you see it reaches just forward of the cockpit, so the sheet can pass through the aft cabin-top fairlead and then to the jamb cleats beside the cabin door. The trouble with the length of the luff is that the foot of the sail is on the point of fouling the forward edge of the cabin. It needs to be shorter so either the standard strop can be used to lift the foot clear of the cabin or a furling mechanism be fitted.

The photo was taken during my first (and only) successful attempt of the Three Rivers Race and it was the only time I ever used the genoa. My crew that year insisted we give it a try. We abandoned the genoa on dropping the mast to pass under the first bridge as it was such a pain to use. When in narrow rivers and you are frequently tacking every 30 seconds and sometimes more often, the hassle of dragging all that canvas past the mast and getting the sail to set properly so slows down the tack that you will gain more ground using a smaller sail - just as you do when you are reefed in strong winds.

You'll also realise that with a hanked-on genoa the size of mine it is impossible to pass the sheets inside the shrouds. The sail catches on them as it fills, wrecking its shape. Of course, that won't be a problem if the genoa is furled a little or, like Brian, you have cleats on the cockpit combing. I did fit such an arrangement on my father's SeaHawk as you see from a photo taken from my report on my "Greg Afloat" site of a Cruise To Outon Broad in 1976. However, the fairlead and cleat were still only used with the genoa outside the shrouds.

Extra Cleats
I recall being a little happier with his genoa as it had a shorter luff and needed the strop on the tack. His mooring was at Dilham and back then I rarely got further than Barton Broad, so I used the genoa on those open waters and, clearly, on the wider rivers of the southern Broads.
Greg Chapman
GregAfloat - My Boating Biography
Reply | Threaded
Open this post in threaded view
|

Re: perfect size of genoa sail when using roller furling at open sea sailing

ianhurley20
This is my slightly different take on genoas.
As Gregg knows from discussions we had during the 3 rivers race and afterwards your sailing background and use of a boat does alter your views. This is particularly so when using a genoa. My main background with sailing and genoas dates from sailing at sea in cornwall in the 60's. (Mainly in a Hurley 20 yacht). Gregg however has more background with inland sailing on rivers. With a smaller jib you can indeed dragg it from side to side at will. With a genoa the technique is different, you have to wait for the wind to push the sail across rather than drag it across or it will indeed snag.
I am sure Gregg will disagree with me but my vote is still for the genoa and a slightly differnt technique to make progress. On my last yacht, a Pirate 17, I only had a genoa although I did have roller furling so could shorten sail easilly and very quickly if needed when the wind speed increased.