Raising boom height - Any thoughts?

Discussions about Cape Dory, Intrepid and Robinhood sailboats and how we use them. Got questions? Have answers? Provide them here.

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Post by rtbates »

I raised our 25D's main by just re-cutting the foot higher at the clew. By about 8". The tack remained unchanged. I notice no difference, excpet I can now stand up under the boom.
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Re: I beg to differ

Post by rtbates »

SurryMark wrote:
Dean Abramson wrote:You might want to start a new thread on the plusses and minuses of dodgers. It would probably get a lot of traffic.
Dan
I'd put in my two cents, and I'd pay another buck forty not to take Tula's dodger away. I do love to see some of that cool water not running down my neck.

On the question of a bimini while sailing: not to take away from the brutal Florida sun, but seriously, how do you check sail trim while you're under a roof? (I do sometimes rig a canvas while at anchor on a rainy night.)
A clear panel in the middle.. IF biminis/dodgers were outlawed I'd have to give up sailing!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Re: Corrected Actual Sail Area Reduction Numbers

Post by SurryMark »

Sea_Runt wrote:
WaywardWind wrote:... I can't image that "about 10%" reduction in main sail area would be anything but a reduction in performance at most wind speeds for a boat that is already a slug at low wind speeds ...
It may ba a good idea to recheck your arithmetic. ....

These corrected arithmetical calculations indicate a reduction of under 3% in mainsail area, far less than the 10% you calculated. ....
Furthermore, we don't know, from the original post, how the sail was cut to raise the boom. For all we know, the sail was shortened at the head, and perhaps more roach was added to reduce the reduction of sail area. And more importantly, changes have always been made to ships and boats not because of some ideological purity about what real sailors do, but for a specific purpose. In this case, sailor wanted shade. If lady Alberg had asked for a bimini, she might have gotten it. More importantly, as an earlier poster said, this is not the most important consideration in deciding whether this particular boat is the one to buy.

On the question of WwW's authoritative posts, I don't know the history, but to me they're like adding an extra high poop on a galleon to make room for the Duke's musicians, or dog kennels and chicken coops at the waist: they add to the varied and pleasant sounds of the forum, and, after all, this is the internet. And besides, I suspected some April 1 influence.
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Steve Laume
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Post by Steve Laume »

I will not attempt to calculate the sail area of the reduced mainsail. It should be noted that the winds are often stronger as the height above the water increases. This would mean that weather the sail area was reduced by 3% or 10% it would probably not equate to a direct reduction in the power the main provided.

This whole issue is just one more of life's compromises. If the boat was going to be sailed in Maine you might want to ditch the Bimini and relocate the boom to it's original position. If the boat is going to be in S. Florida or the Islands then it might be best left alone.

If the boat is in other ways what you want for the money you are willing to pay, this doesn't seem like a deal breaker either way, Steve.
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Post by Kevin Kaldenbach »

Of course the center of effort is raised but at a reduced value. So what your saying is if we cut the whole sail away except for the top 3 feet then with all of the center of effort being at the top 3 feet of the mast the boat would be sailing around with its rail in the water all of the time. I kind of figured it would not sail at all.
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Re: Huh?

Post by Maine Sail »

WaywardWind wrote: A dodger means the boat is motored more often.
Can you please support your, unsupported, and purely made up factually stated data for us? I'm sure we'd all like to see that white paper.. :D

BTW every one of my friends who have circumnavigated or cruised for multiple year stints has a dodger, every one. Our own boat did 30k nm in 5 years from Maine to Europe to Labrador to South America to Alaska and beyond all with a dodger.

The percentage of cruisers with dodgers is quite high. Heck I even race on boats with dodgers, and against boats with dodgers and without and we remain competitive with or without the dodger, no motors when racing..:wink:
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Post by Steve Laume »

This thread was about boom heights and biminis but I would say that boats with dodgers are sailed more often.

Our dodger stays up all of the time. The only time it does come down is if there is the threat of a hurricane. There are lots of days I would not want to be out at all if not for the dodger. The reasons could be cold wind with spray and or rain. Or hot sun, were we huddle under the protection of the dodger for shade. It is also very nice to have a dew free zone in the cockpit for that first cup of coffee in the morning.

I am sure these conditions could all be addressed with protective hats and sunscreen or additional layers of clothing and foul weather gear. The point is that we sail for pleasure and the dodger makes the experience much more pleasurable weather you are sailing or motoring, Steve.
WaywardWind

High school math and circumnavigation

Post by WaywardWind »

29.75 feet (P) = 357 inches.

Ten inches less = 347

New, reduced sail area = 347/357 = 0.97198879551820728291316526610644 * 167.xx ft^2, or not quite a 3% reduction.

Sorry, my swag calculations came out a tad higher.

Of course, an ONLY "not quite" 3% reduction in sail area on a miserably undercanvassed boat in light air is MUCH better than a "near 10%" reduction in sail area.

Now ...

... let's consider the raising of the CE of the mainsail in the modification of the boom height.

The center of area of a right triangle (CE of the main sail in this case) is "approximately" up one-third (from the boom) and in one-third (from the luft).

Therefore, the orginal CE of the mainsail is "about ten feet (1/3 of 29' 9") up and and a tad less than four feet (1/3 of 11') back" PLUS the distance the boom is above the deck 4' 3" on a CD-27), a total of above 14 feet 3 inches.

In other words, about 14 feet above the deck and a tad less than 4 feet aft the mast.

MODIFIED BOOM sail CE is up about 1/3 the 28 foot 9 inches of the new luft and the same aft of the mast, PLUS the NEW height of the boom above the deck, which is the orginal 4 foot 3 inches plus 10 inches, or 5 foot 1 inch, a total of about 15 feet 1 inch

In other words the NEW CE of the modified boom sail is *** 10 *** inches higher. 14' 3" = 168". 15' 1" = 181"

181/168 = 0.107142857168428571428571428665, or a nearly 11% INCREASE in CE above original.

Except in light winds, that is a LOT.

Now, let's address the concept of sailors sailing and circumnavigators dodgering/biminiing and "waiting for a weather window".

A sailor is defined as one who has his sails up and pulling, NO ENGINE running (listen to a VHF on a beautiful sailing day to hear the number of "sailors" who turn on their engines so they "can point higher"). If the engine is running, the boat is legally a motorboat.

NOW, check with circumnavigators (today) who kept ACCURATE logs of their engine use and you'll find that even the most ardant sailing enthusiast is horrified to find he/she motored **over half the time** at sea.

Why did they motor?

Because their boats wouldn't sail in winds under 10 knots (what with the dodgers, biminis, jerry jugs, kayaks, dinghies, davits and other "required" stuff turning their boats into motorboats with sticks).

Now consider prudent mariners do not purposely "go out there" in likely stormy weather, which means they choose their seasons for passages. Reliable reports (and pilot charts) indicate that most passagemakers see 99% of their winds under 10 knots.

Take a boat with junk on the deck and NO light air sails, (and 10 days supply of engine fuel), and the motor gets turned on.

Forty years ago, EVERYONE sailed, because well it was called sailing for a reason. Today, most everyone motors well over 50% of the time (the eastern Med, what a thousand miles from the Atlantic, is littered with marine engine rebuilders because "sailors" wore their motors out). Better sails, better weather forecasting, and they turn on the motor. Anecdotal evidence indicates some "sailors" in the Caribbean (with its great trade winds) wait for months on end for "a weather window". Reportedly, Ft Lauderdale has more than 1,000 working marine diesel mechanics.

A CC-27 is not everyone's first choice for a circumnavigation, but if it were someone's choice the prudent mariner would clear the decks of ALL junk and lay in a supply of light air sails.
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Post by Jeff and Sarah »

You'd get just as much additional healing moment by adding a windex or monitor to the top of your mast. Not many of us are concerned about the weight of those, nor the vhf antenna or anchor light when it comes to sailing performance, but a few pounds of weight at the top of a 40 or 50 foot mast really starts to add up in healing force. I still consider myself more of a racer than a cruiser, but I just can't begin to see why anyone would care about the detriments of raising the boom on a small full keeled boat. If the change allows a bimini, and a bimini is what you want, why not do it? Would you rather have that extra couple tenths of a knot when you probably aren't trying to go anywhere in particular to begin with, or would you rather be comfortable when you go out and enjoy a day on the water?

We also still don't have enough info to even tell if the boat sails worse or not. If the sail was changed to loose footed, the boat might even sail better now- who knows? Someone else asked if more roach was added- that's a great question. What is the condition of the sail? I'd be willing to race a CD27 with a raised boom flying brand new sails cut for the geographic region against any stock CD27 with 5, 10, or 20 year old sails any day.
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WaywardWind

Motoring

Post by WaywardWind »

Let's end this discussion because it is no longer about sailboats, but rather floating weekend homes.

Kawasaki used to make a rather nifty looking retro "cruising" bike with an excellent engine, good brakes, good electrics, excellent suspension ...

... but it scraped the running boards going around every corner. Today, used ones sell for half what similar bikes of the same era -- which don't scrape the running boards on corners -- sell for.
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Post by Jeff and Sarah »

Wayward,

Any chance you have some photos of your highly tuned, non-home, sailing machine? I'm sure we'd all like to see a CD that has no sacrifices for comfort and gets underway only under sail with nothing but the thought of being a 'real sailor' in mind.

Jeff

-typed from aboard my actual home (CD33) in the comfort of air conditioning (83 outside but a cool and comfortable 73 inside).
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Re: Motoring

Post by Russell »

WaywardWind wrote:Let's end this discussion because it is no longer about sailboats, but rather floating weekend homes.
Your hate for dodgers/biminis is really curious to me, I seem to recall a previous thread where you also strongly expressed this. Why do you feel so strongly about what other sailors prefer? This holier then thou attitude makes me laugh. Is my boat not a real sailboat because it has a dodger (which I hope to make into a permanent hard dodger one day) and a fixed bimini (yes, my bimini is welded in place to the radar arch, it cannot be removed). Am I not a real sailor either because my boat isnt a real sailboat?

People buy cruising sailboats because they are also floating homes, comfort is important. If I wanted nothing more then to daysail and for it to be purely about sailing, I wouldnt own a CD36 and likely not a CD at all. You wouldnt catch me doing long offshore passages without a dodger, no thanks, but guess what, its still real sailing. And spending years in the caribbean without a bimini, keep your SPF whatever clothes, I want shade. I have many thousands of miles under my keel sailing, cruising and living aboard full time. You can take your holier then thou attitude and shove it you know where because my boat IS still a real sailboat. The CD board isnt a place we judge people, you can express your preference to not use biminis or dodgers, but suggesting others are less sailors because they do prefer them isnt welcome.
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