HC14 to Sailing Trimaran!

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narfi
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Re: HC14 to Sailing Trimaran!

Post by narfi »

Jaysen wrote: Fri Jan 29, 2021 11:34 am I thought about this over night...

I have some concerns about needing stays/shrouds on this thing...

1. The stays/shrouds will put a lot of downward pressure on the keel seam under the mast and a lot of upward pressure on the thwarts (or wherever you decide to attach them).
2. Stays/shrouds need to be tensioned properly. That means lots of setup time.
3. Stays are kind of a performance things in little scooters. Like race performance. I think you will get MORE than enough speed and might want to consider #2 over performance.

I think I would recommend a config that uses a capturing step and a mast partner over stays/shrouds. A lot simpler.
Yes, functionality over performance for sure, though I do want it to look nice and be enjoyable to play with. (both for me and the upcoming batch of teenagers)
This is where my lack of experience really shines..... a big stick poking up into the sky with a kite attached to it....... is two points of attachment a foot apart enough to fight that much leverage? I even had someone go the other direction with recommending that I would likely need spreaders to prevent the mast from acting like a wet noodle.... I just don't know the physics of it, nor the math to calculate anything like that other than reverse engineering or following someone elses plans.

Jaysen wrote: Fri Jan 29, 2021 11:34 am You also need to consider the CoE of the sail for the location of the dagger/lee board. if you don't get the right balance you wind up with either a frustrating or a dangerous end state. If the CoE is behind the dagger, you wind up with "weather helm" where the boat constantly points into the wind. This is frustrating as you wind up fighting to keep her on course. If you get COE in front of the dagger you have the apposite problem... always pointing lee. The problem here is that you wind up with a serious gybe potential and an increased risk of pitchpole/bow stuffage.

All the plans I have show the CoE aligned with the keel/dagger (it is actually aligned with the "center of resistance" on the non-BBC plans, I don't see a marked point on the BBC plans).

Might be worth asking JM to weigh in on mast and dagger/lee board placement.
yes, I was going to figure out daggerboard placement last as I do know they need to be balanced with the sail. I am planning to put them in the outriggers just so that its one less thing attached to the original canoe, I am sure I will need to do a few minor attaching modifications to the canoe but when its done ideally I can just bolt the canoe to beams and launch, then when I want a canoe I can unbolt it and its ready to go.... simple in my mind anyways......

My main project right now is the airplane, but I purchased the plans before they were completed, so this is my 'stay out of trouble' project while I am waiting for more things to do on it. It will at least keep my brain busy during the winter, and then hopefully have it figured out enough in the spring that when I have a good window to do the work put it all together. Its good and bad.... good that I can ponder things longer and sort out little details, bad in that things are simpler for me when I am physically doing them and stuff begins to make more sense and fall together more easily. (at this point I don't know what I am over thinking and what I am underthinking)
Last edited by narfi on Fri Jan 29, 2021 11:55 am, edited 1 time in total.

piperdown
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Re: HC14 to Sailing Trimaran!

Post by piperdown »

I wish you guys would stop talking in a foreign language because not even Google translate is helping me figure out what you are saying...... :lol:
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"Give an Irishman lager for a month and he's a dead man. An Irishman's stomach is lined with copper, and the beer corrodes it. But whiskey polishes the copper and is the saving of him." --> Mark Twain

narfi
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Re: HC14 to Sailing Trimaran!

Post by narfi »

piperdown wrote: Fri Jan 29, 2021 11:54 am I wish you guys would stop talking in a foreign language because not even Google translate is helping me figure out what you are saying...... :lol:
Me either.....
College was easy for me, math, science, English, economics, etc... never took notes, hardly did homework, showed up and aced all the tests. Hardest I ever worked was Spanish, I studied hours every day religiously took notes in class, went over the homework multiple times, etc.... midway through the class I went to the teacher and asked if there was any way I would be able to pass, extra credit, anything, she said 'no', so I had to get a special drop for the class so I wouldn't have the marks against me. My brain just cant process other languages :/ and 'sailing' seems to be a language of its own.

narfi
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Re: HC14 to Sailing Trimaran!

Post by narfi »

narfi wrote: Fri Jan 29, 2021 11:52 am
yes, I was going to figure out daggerboard placement las
Just realized this is simple, I just need to place the daggerboards same distance from the mast as they do the centerboard on the 420 which is well documented.

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Re: HC14 to Sailing Trimaran!

Post by Jaysen »

narfi wrote: Fri Jan 29, 2021 12:20 pm [quote=narfi post_id=484328 time=<a href="tel:1611939129">1611939129</a> user_id=79866]

yes, I was going to figure out daggerboard placement las
Just realized this is simple, I just need to place the daggerboards same distance from the mast as they do the centerboard on the 420 which is well documented.
[/quote]

This changes if you plant them out on the outriggers. Consider the placement in three dimensions. Your thinking is longitudinal placement on the keel line. Now consider how infrequently the wind will be a directly on the beam. As the wind moves off that beam angle (and you move the sail to accommodate) the CoE moves forward. When wind is dead aft on a shroudless config the CoE is actually even with the mast. We are still considering this from the “beam” view.

Now move to a transom view and you’ll see that the CoE not only moves forward but OUTWARD. You now have a lever created between the CoE/boom and the CoR/keel with the mast as the fulcrum. The CoR is countering the push of the sail against 2 different fulcrums in 3 dimensions.

Now factor in moving the CoR out to an outrigger. As the CoE moves forward you actually have a LARGER change in the relative resistance of to the forces created. The net effect is to magnify the apparent distance with between the CoE and CoR. AKA the CoR is more AFT than it actually is.

Look for some plans showing cameraman profiles (tris even better). All the ones I’ve looked at show the CB/keels further forward than they would be on a mono. The other change you will see is that the keel/cb shoe is shallower and looooong. My understanding is that it effectively addresses most of the issues while allowing for a shallow draft.

That’s how I understand it anyway.
My already completed 'Lil Bit'. A Martens Goosen V12 set up to sail me to the fishing holes.
Currently working on making a Helms 24 our coastal cruiser.
“Mark Twain/Samuel Clemens” wrote:Eat a live frog first thing in the morning and nothing worse will happen to you the rest of the day.
Jaysen wrote: Mon Apr 29, 2019 3:44 pm I tried to say something but God thought I was wrong and filled my mouth with saltwater. I kept my pie hole shut after that.

narfi
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Re: HC14 to Sailing Trimaran!

Post by narfi »

Here is the 420 outline,

Image

and a picture of a big cat,

Image

very unscientifically they look similarly placed, I will do a lot more research for sure.

As to keels vs daggerboards vs centerboards vs a combination..... I have seen all of them in different multihulls but the two dominate ones are long shallow 'mini keels' used for cruising boats, they offer more boyancy less work or maintenance and a flat surface to beach on if you want, the downside being they can not reach as high(a big issue with multihulls I guess) and they are deeper draft(even though mini, they are always there), the other being daggerboards which you see on more performance oriented racing or performance cruising multihulls, they do require active adjustment, when pulled up they have a much shallower draft and when deployed can reach much higher. (If I am using the terms properly....) Sometimes a boat with a daggerboard will have very tiny beeching keels as well but they do not seem as common, most are either keels or daggerboards.
Of course this is all talking about larger boats which has been primarily what I have read and researched about this last year, I am now looking more into smaller solutions for this project which may or may not be the same or different.

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Jaysen
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Re: HC14 to Sailing Trimaran!

Post by Jaysen »

I'm irritated that I could not find anything with clear COE marked...

Here is a cat that has the closest numbers to a 420 that I could find with a profile elevation: https://sailboatdata.com/sailboat/yacht ... -catamaran

Here is the 420: https://sailboatdata.com/sailboat/420

Another key point with all of this is the difference between multi sail (main + jib) and single sail (main only). The weighted CoE for each sail is factored into a multi sail configuration.

edit: This is fun for me. I'm sure you will find the right combo for you all up there.
My already completed 'Lil Bit'. A Martens Goosen V12 set up to sail me to the fishing holes.
Currently working on making a Helms 24 our coastal cruiser.
“Mark Twain/Samuel Clemens” wrote:Eat a live frog first thing in the morning and nothing worse will happen to you the rest of the day.
Jaysen wrote: Mon Apr 29, 2019 3:44 pm I tried to say something but God thought I was wrong and filled my mouth with saltwater. I kept my pie hole shut after that.

narfi
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Re: HC14 to Sailing Trimaran!

Post by narfi »

Jaysen wrote: Fri Jan 29, 2021 2:31 pm Another key point with all of this is the difference between multi sail (main + jib) and single sail (main only). The weighted CoE for each sail is factored into a multi sail configuration.

edit: This is fun for me. I'm sure you will find the right combo for you all up there.
Something good to look at for sure,
I realize that a main sail will be different than a main+jib, however those boats are sailed with one or both without moving location so there must be a compromise chosen there right?

yes fun for me too, I enjoy the conversation and thought process, hopefully I haven't done or said anything to discourage it :)

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Re: HC14 to Sailing Trimaran!

Post by Jaysen »

narfi wrote: Fri Jan 29, 2021 3:17 pm
Jaysen wrote: Fri Jan 29, 2021 2:31 pm Another key point with all of this is the difference between multi sail (main + jib) and single sail (main only). The weighted CoE for each sail is factored into a multi sail configuration.

edit: This is fun for me. I'm sure you will find the right combo for you all up there.
Something good to look at for sure,
I realize that a main sail will be different than a main+jib, however those boats are sailed with one or both without moving location so there must be a compromise chosen there right?

yes fun for me too, I enjoy the conversation and thought process, hopefully I haven't done or said anything to discourage it :)
You have not. I just wanted you to know I'm enjoying the thinking since I'm not "building" right now.

On multis sail configs, there is a HUGE compromise when sailing single. The only time there isn't is downwind. Then the goal is balancing to keep the boom under pressure and the bow out of the waves (if you look at symmetrical spinnakers under full wind you will see how they lift the bow when compared to wing and wing jib+main). In my experience, a fractional rig relies on the jib to counter act HUGE weather helm as wind increases. In mast head configurations, the main us used to counter the jib push to windward. The term "jib driven" or "main driven" is what folks use to differentiate the power sail from the balance sail in the racing community here.

It seems like a "duh" moment when you think about it. If you have a massive jib compared to the main, the jib is going to provide more power. If the main is larger, then the main provides power. But since the MOST power comes from both sails, the designers of race hulls will design from that starting point. that means if you reduce sail via reef, or if you douse a sail, you will have handling issues. I can verify that a J30 (main driven) handles like crap with just the main, just the sail, or unequal reefing. Same with a Beneteau (jib driven) 523, 473 and 323.

For you and your crew, if you are planning on just one sail, just work then CoE on the sail, then plant the CoR under it. Given how small the whole thing is, I would be tempted to just run a skeg down the keel of each outrigger with a leeboard on the canoe (at CoE) if you find it is needed.
My already completed 'Lil Bit'. A Martens Goosen V12 set up to sail me to the fishing holes.
Currently working on making a Helms 24 our coastal cruiser.
“Mark Twain/Samuel Clemens” wrote:Eat a live frog first thing in the morning and nothing worse will happen to you the rest of the day.
Jaysen wrote: Mon Apr 29, 2019 3:44 pm I tried to say something but God thought I was wrong and filled my mouth with saltwater. I kept my pie hole shut after that.

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Re: HC14 to Sailing Trimaran!

Post by VT_Jeff »

narfi wrote: Fri Jan 29, 2021 3:17 pm those boats are sailed with one or both without moving location so there must be a compromise chosen there right?
My current boat (C&C 29MKII) sails great under jib alone, my previous 2 boats did not.

As you move the CoE forward and aft, you're going to add helm, lee and weather(edited, I think it's right now...) respectively. So under jib alone, CoE moves forward, more Lee helm. Main alone, CoE moves aft, more Weather helm. A safe boat should have some weather helm so in case you fall off, it will circle you like a jetski(not really).

I would get the mast and the outriggers on, clamp a leeboard to the canoe and sail it for a while on different points of sail, move the board around, see what feels good. I think Jaysen recommended about the same.

Awesome project BTW!

Edit; I'm feeling lysdexic trying to remember the weather/vs lee details, been too long since I thought about that stuff.
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