SailNet Community banner

1 - 20 of 23 Posts

·
Registered
Joined
·
1,000 Posts
Discussion Starter #1
I am considering modifying my MacGregor 26X
from a fractional sloop rig into a cutter rig to increase sail area and add power. I will be mounting the new headstay 3'' above the other one and attaching the other end to a 6'' bowsprit. This will give me an "I" measurement of around 26'' and a "J" of 16''. The original headstay has an "I" of 24'' and a "J" of 9'' 8". My question is that does the angle of both headstays have to be the same? To match the angle I will have to cut 3'' off of the bowsprit giving me a "J" of around 13''. Does this angle make any sort of difference in the performance of the sail? The 6'' bowsprit would give me a potentially large genoa. 300+ square feet.

Any opinions or comments?

Larry,
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter #2
you will probably have to add running backstays to support the mast where the new load is present.
eric
 

·
Registered
Joined
·
734 Posts
Mr. Brink
If you plan to add a cutter rig and sail you will most likely have to structurally reinforce the fore deck area to accommodate the stay. This will probably be major work and could compromise the usage of the vee berth. In my most humble opinion this boat is not worth the time, headache or money to make such a modification. Unload that piece of Tupperware and find a better boat that comes from the factory with the right amount of sail area and ballast.
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter #4
wow that is a really a rude remark.
i think the mcgregor has its market and its uses and i don''t believe the purpose of this forum is to put people or boats down but to share knowledge and friendship.
incidently what type of tupperware do you own?
eric
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter #5
As far as having the two stays at the same angle that is not required. Having had a cutter rig with not much clearance between the stays it can be a real hassel to get the topsail through. One problem you might create is a lee helm as the center of effort will move forward a fair amount. Adding an asymetrical spinaker might be more practical
George Hughes
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter #7
Greetings,with an asymetrical spinnaker you actualy will not be able to use it going "directly"downwind. They work great in light airs from a broad reach to nearly a close reach. Good luck,Dave
 

·
Registered
Joined
·
734 Posts
Keep your powder dry...please. Sometimes the truth hurts, but be honest with yourself, the Mac 26 is a small lake "econo" (read cheaply made) sailboat. Perhaps my comment was PI, get over it!
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter #9
Larry,I am planning to do the same thing on a grampian26(Canadian built boat)and was asking my self the same questions you do.Thanks to george for the answer on the stays angle,one problem solved.Besides this important element of the modification and like george said it,I am aware of creating a leehelm problem by moving forward the center of effort.Creating leehelm is not desired at all for safety reasons and would generate some drag that could counteract the increased power of the added sail surface.I see two options to rebalance the boat;Move aft the base of the mast and the chainplates with structural reinforcement under the base of the mast.True cutters have their mast set well aft,abaft 40 percent of the waterline lenght.This I guess,to compensate the fact that their foretriangle is larger than the mainsail.This brings me to the second option of a larger mainsail(full battened?) instead of moving the mast.I think it could be a viable one and would generate some more power that you are looking for.Good luck with your project!You can take a look at the way I am planning to install my bowsprit on my web site at www.geocities.com/grampi2000/grampian26.html

grampi2000
 

·
Registered
Joined
·
3,622 Posts
As mentioned in other posts, having the center of effort moved so far forward by the additional sail area of the new jib will mean you may hardly be able to head upwind at all. Macgregor designers built the boat with the sails and mast it has for a reason. Adding more in various places may place loads on the rig and structure that they cannot withstand. Trying to make it work may be more effort than it''s worth. For example, tightening the suggested (and likely quite necessary) backstay to tighten the forestay would essentially end up pushing the base of the mast through the maststep and cracking the keel. This is similar to what happened to the America''s Cup boat that split in two and sank a while back. If you can keep the rig in the boat, flying an oversized chute downwind can be fast and fun, but that works because the boat is balanced more easily for&aft than from side to side. Trying to increase sail area for upwind is a whole different balancing act. IMHO along with others here who suggest that if you need a bigger boat with more sail area, get one.
 

·
Administrator
Joined
·
9,189 Posts
I think that what we are all trying to tell you here is that any properly designed boat is designed as a system. The rig is designed to be proportionate to the stability of the boat and to the center of lateral resistance in the boat. Properly done, the boat should have a neutral helm and proper stability for normal conditions that the boat is expected to encounter. When you look at a budget counscious trailerable, there are issues of structure as well.

When you talk about adding a 6 foot bowsprit you are talking about a major change in the center of effort. (I once changed the rake of the mast on a 41 footer by 6 inches at the top of the mast and the helm went from weather helm to lee helm. You are proposing a change that will really make the boat dangerous because in a gust the boat will fight to turn down away from the wind and can lead to a serious knockdown.

Beyond that, having actually owned a 26 foot on deck 1939 Stadel Cutter, Cutters are a real pain in the butt on boats this small. It is not easy to tack the genoa through the slot.

If you absolutely feel that you must change your sail plan I would suggest a couple ideas. First I would think of adding a more modest bowsprit (18-24 inches or so) and move your forestay out there. If I remmber the Mac 26x correctly the boat has a fractional rig so I would consider going to a masthead rig. This will probably mean raising the spreaders and upper shroud attachment point. Then I would also add a boomkin and a longer boom so that the center of effort reamined where it is. This is adding additional strees on the boat so that shroud attachment points might need to beefed up. Lastly there is the stability issue. Having watched these boats in a breeze, they do not have great quantities of reserve stability and so you might want to look at increasing the boat''s stability as well.

Now, as some of the other posters have suggested, the Mac may have some under considered virtues, but as a well rounded sailboat in a wide range of conditions, the Mac is somewhat lacking. If you take the price that you can get for selling your Mac and add to it the cost to modify the rigs, there are a lot of other better boats out there that you can probably buy for less money.

Respectfully
Jeff
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter #13
I think that you are right that 6'' is way too much. I have been doing some number crunching and found that if I shortened the bowsprit to 2'' and attached the forstay to the masthead the sq feet of the for-triangle would be 152'' with the main area 151''. The orginal square footage is 117 sq feet. Would not the helm be more balenced with the modifiacation then without?

Larry.
 

·
Registered
Joined
·
4 Posts
A sailboat is a collection of many different "balance points" and if any of these are moved (because of some modification) you will need to do something to bring the overall balance back into postion. You can''t estimate the balance of the sail plan on the sq. ft. area of the sails alone. You need to know there the center of effort is for each sail, and then the combination of the two or three etc. The combined center of effort is the point everyone is talking about. And by adding size of the fore sails you are moving that center of effort forward, add to that, the fact you''re moving the foresails farther forward again moving the center of effort of those sails even more forward... but the center of effort of the main sail didn''t move, so the combined center of effort is farther forward than the boat was designed to handle.... the result count be not good.

As someone else stated, a boat is a comeplete system. changing one thing has affects of other areas, sometimes to the point of actually hurting proformance more than the change helped it.... let alone the safety considerations.
 

·
Registered
Joined
·
5,067 Posts
Very good point concerning .... balance points.
Also consider that what balances a boat is not ONLY the *geometric* total of balance points of a sail plan; but rather and additionally, those forces generated by the sails that are *dynamic* (including dynamic efficiencies). If one would simply plot the geometric centers of effort, you could be seriously remiss if you excluded the dynamic effects. Dynamic effects are usually obtained by experience and history ..... and usually are within the realm the knowledge of a good sailmaker or aerodynamic theoritician.
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter #16
Well it certainly seems that I am going about my quest for more windward speed all wrong with the Cutter rig. What would be the best solution to increase windward performance?

Larry,
 

·
Administrator
Joined
·
9,189 Posts
Larry, as much as I hate to say this, you are really fighting an uphill battle. There are a lot of factors that control how well a boat goes to windward. The sail plan is but a very small part of the problem. Going up wind you tax a boat''s stability,foils and hullshape.

It works like this. To really get good windward performance you need a higher aspect ratio rig (taller rather than longer). High aspect ratio rigs generate more drive with less drag. This would mean increasing mast height and increasing main and jib luff length without changing the horizontal dimensions of the rig.

For this to yield much of an improvement you will need better sails. Mac''s original sails are really junky- stretchy and not very well shaped.

Then there is angle of attack. With the new taller rig lead angle will become the problem. To improve this you would need to add inboard jib tracks and shrouds, and a high quality traveler and vang.

Of course none of that will help much is you don''t imporve the foils and stability. The taller rig will make the boat want to heel more. The standard rig is designed to feel stabile by not over-canvassing the boats limited stability. With the taller rig and greater sail area you will heel more and so make greater leeway negating any gains that you made in your sail plan.

Then there are the foils, keel and rudder. These are proportioned to your smaller rig size and to the limitations of the hull shape and rig. A new keel and rudder would be necessary to get better windward performance. The keel would probably want to be lead which would increase stability over your current glass and iron board. Of course then you will need to beef up the structure and lifting equipment to handle the greater weight and loadings of the heavier centerboard.

When you get done with all of that you will have a boat will still be limited in its pointing ability by its hull form. That said, if you did most of the above, pointing ability would improve.

When all is said and done, new sails would probably make the biggest difference but unless you did the whol program you would never achieve a boat that truely goes to windward very well. With all due respect, if you really want a boat that sails well on all points at a reasonable price you would be far ahead to change boats. Using any kind of objective analysis, there is no way it would ever make sense to put that kind of money into making your Macgregor a better sailer. There are really better built and better sailing boats out there for the money and frankly, if you care about how well your boat sails that would be a better way to go.

Respectfully
Jeff
 

·
Registered
Joined
·
6 Posts
I have a cutter rig 48'' C&C. I have to say I
NEVER use the staysail & the genoa
(130) at the same time. Too much
turbulence. It just isn''t worth the effort.

A roller furling Genoa with a padded luff which maintains sails shape even partially furled is going to give you the ability to get maximum useful sail up as well as the ability to shorten sail easier than depending on the staysail.

I saw someone say that the forestays need not be at the same angle. That may be, but it seems like it would look sort of
strange if they are not.
 

·
Registered
Joined
·
1 Posts
I have thought about the idea of a removable inner forestay. Adding this to my Hunter 30 would entail reinforcing the foredeck with a cable leading through the vee-birth through the cabin sole to the keep. Running backstays would be needed to reinforce the mast, as noted in another response to the "cutter" conversion question. When you figure the cost of the boat modifications, the cost of a new, custom sail, the unknown change in performance, etc. it is probably not worth the hassle. Much better to spend the money on other things, or get a different boat if a cutter is desired (I agree with the comments of the other responders). One option instead of another forestay would be a "gale" sail (made by ATN) which mounts over the furled headsail and which can perform in heavy weather, with or without a storm trysail. But I guess I am getting off the topic; the owner of the Mac 26 wanted better upwind performance. Probably with that design, the best upwind performance would be with the existing sail plan but with new, good quality sails. Turning on the motor would also help.
 
1 - 20 of 23 Posts
Top