Yam 25 Mk II Boom

[alturaam]

Hi folks,

I will be replacing the sails on my Yamaha 25 Mk II as the main is baggy and blown. Same for the headsails but they are still useable. As I took measurements (I,J,P,E) for sail dimensions, I came to the conclusion (duh!) that my boom is not a stock or original boom for this boat. It is 9'9" long and even though it is labeled "Yamaha," it was longer than the spec in the manual, which is 2.75m or just a hair over 9 feet, which is about the length of the foot of my main. Based on the Yamaha fleet dimensions, this boom was probably for a Yamaha 30.

I did not think getting a bigger main to use up the full lenght of my boom would be a good idea as I would merely excacerbate or increase weather helm by moving the center of effort for the main further aft, besides being simply over powered.

The foot of my sail has a bolt rope and it is not loose-footed, like many of the Yamaha 25s that I see in pictures (or on Youtube videos).

An old thread recommended a RigRite 4F boom. I'd like to know if it is possible to order an original boom from Japan or if there are suggestions for an equally suitable one from some the U.S. spar makers.

Thanks all

 

[Syntonos]

Yamaha parts / SAILS Timely Post

Wow, this is timely!
I just had my boat measured for sails Tuesday. Having my Local Ullman loft rethink the sail plan a bit, raising boom slightly and full hoist 115% headsail. They have a 25% discount right now, if you are willing to wait till spring for your sail, so it will be a while till I can report on how they came out.

Regarding your boom, As it isn't a sophisticated extrusion I'm thinking a spar manufacturer would have something close. You may even find something at your local boat salvage.
9ft is the correct length.
If you want to check out Bob's Site Yamahasailboats.org I believe he has an e-mail contact for Yamaha Japan. I have it some where if you can't find it on his site. It has also been posted on this forum if you search back.

Cheers
Syntonos

 

[alturaam]

Thanks, Syntonos. My boom has a rectangular cross section with an outhaul that doesn't work very well. I've seen some used 9' booms on Ebay in really crappy condition, but I'm sure if I poke around here in Annapolis, I might something. Someone on an old thread had a contact email for Yamaha in Japan, a certain Mr Suzuki. I sent an email earlier and got an out of office reply. I will first get a new boom next will come a new main.

Wow, this is timely!
I just had my boat measured for sails Tuesday. Having my Local Ullman loft rethink the sail plan a bit, raising boom slightly and full hoist 115% headsail. They have a 25% discount right now, if you are willing to wait till spring for your sail, so it will be a while till I can report on how they came out.

Regarding your boom, As it isn't a sophisticated extrusion I'm thinking a spar manufacturer would have something close. You may even find something at your local boat salvage.
9ft is the correct length.
If you want to check out Bob's Site Yamahasailboats.org I believe he has an e-mail contact for Yamaha Japan. I have it some where if you can't find it on his site. It has also been posted on this forum if you search back.

Cheers
Syntonos

 

[Ted]

Yam 25 mMk II Boom

Can't you cut your existing boom to the proper length? If your gooseneck fitting is removable, this should be a simple modification. I would guess that shipping a boom from overseas would be cost prohibitive.

 

[Syntonos]

Y25 boom extrusion

The original extrusion is oval , the rectangular cross section is definitely off base. You probably have the same problem with the outhaul as my boat. the aluminum slug has corroded into slot. I've gone with a loose footed main and plastic slug for easier sail tune (less drag in slot) I'll miss the shelf though, great place to put misc. junk ( and lose it)!
I know what you mean regarding used booms. Mine fits that category. Lots of old holes from years of re rigging. I'm considering replacing mine also. keep me in mind if you find something. I'll do likewise.

 

[Ted]

Yam 25 MkII Boom

Syntonos, can you provide the measurements of your boom? (width, height and length) I have a new boom that may fit a Yamaha 25mkII.

 

[alturaam]

You know, that is actually an excellent idea and something that didn't even enter my mind. My only concern would be the location of the mainsheet along the boom after it is cut. The mainsheet would be much closer to the end of the boom which I suppose would be OK. I'd have to look at it. With a new 9' boom, I suppose my mainsheet attachment would move forward slightly.

Can't you cut your existing boom to the proper length? If your gooseneck fitting is removable, this should be a simple modification. I would guess that shipping a boom from overseas would be cost prohibitive.

 

[alturaam]

Re: Y25 boom extrusion

Yes it is rectangular and there is Yamaha plate on it, which made me think it was original. The Yamaha contact in Japan replied to me ( a Mr Suzuki) and told me that they no longer support these boats as they have been out of production for more than 20 yrs. As to a new boom, I am now indifferent to a bolt-roped foot or a loose footed main. I just want an outhaul that works.

 

[Ted]

Yam 25mkII Boom

If your outhaul fitting is removable, you can cut that end and your main sheet attachment location wouldn't change.

 

[Syntonos]

boom measurement- sure thing

I'll Measure up the boom next week and post some pics of fitting.
Fortunately I have another Y25 on my gangway. I'll take a look and see if they are the same.

 

[Syntonos]

loose footed main vs. boom bolt slot

FYI,
I chose to go loose footed Main to reduce the drag that a bolt rope slot creates helping the outhaul. It's function over form.
I prefer the look of a bolt rope with shelf as that is what I learned with, but, bolt ropes shrink over time and affect sail shape. I still stuck with a luff rope on the main, prefer the sail control of the luff over slugs.

Just my 2 cents

 

[alturaam]

FYI,
I chose to go loose footed Main to reduce the drag that a bolt rope slot creates helping the outhaul. It's function over form.
I prefer the look of a bolt rope with shelf as that is what I learned with, but, bolt ropes shrink over time and affect sail shape. I still stuck with a luff rope on the main, prefer the sail control of the luff over slugs.

Just my 2 cents

Thanks Syntonos,

I have warmed up to the idea of a loose footed main after having crewed on J-105 and a J-80, which both use loose footed mains. That set up also appears to be mechanically superior for the outhaul.

My main luff has slugs which are extremely useful to me because I singlehand a lot. That allows me to raise the main from the cockpit (with the slugs held in by screw on plates to the mast).

BTW, after taking repeated measurements for I,J,P,E and comparing them to the specs on Yamahasailboats.org, it appears my rig is that of a Yamaha 25 and not a MKII as I had previously thought. Although, my top of mast to boom measurement is that of a MkI,, which implies that I am using a MkII sail on a shorter mast which in turn, logically makes for a lower boom height. All other measurements appear to be that of a Yam 25. If I were to have the boom moved higher, I would have to us a smaller main, which I am not averse to. That might decrease the amount of weather helm on the boat.

 

[Syntonos]

Y25 Sail Plan, Racing thoughts

The Y25 is definitely headsail driven. When I first hopped on the boat, the main seemed small compared to my 17' Thistle which is known for their huge mains. As my sail maker put it the main on the boat is more of a trim tab for the headsail.
Sounds like you've crewed some serious boats. All this talk of sail performance is getting me amp'd up to go racing again. If these new sails work out I may have to go PHRF racing.

Speaking of racing , getting ready to watch A cup and see if Oracle can pull another rabbit out of the hat. Went to SF for first 2 races... NZ is way ahead on the learning curve. Just no luck! The boats are crazy!!!

 

[alturaam]

Hi Sytonos, yes, I've crewed on serious boats but I am not a hardcore racer. I have uploaded a photo of my boom. You can see how much longer it is than it needs to be> Besides cutting it, getting a new boom is another option.

 

[Syntonos]

Y25 Boom

Wow,
That is quite a departure from the original boom. I'll photo doc the standard boom/sheeting. The problem replacing a Y25 boom will be the boat specific cast fittings on each end. I'd consider cutting down your existing boom as was suggested earlier if the outhaul will work with your sail, or..... starting from scratch if you want to get back to the 9ft boom. It's only $$$$$.
Stay tuned.

 

[alturaam]

Right. Actually, the cross section (as you can see) is not rectangular but trapezoidal. My first option is to have it cut at one of the local spar shops and the end fittings re-attached. The boom has an additional loop forward of the current one for the main sheet. Note that my main sheet is attached to the boom in only one place, not like the standard two-pulley set up that I've seen on other Yam 25s. I may go with a loose footed main later on.

Wow,
That is quite a departure from the original boom. I'll photo doc the standard boom/sheeting. The problem replacing a Y25 boom will be the boat specific cast fittings on each end. I'd consider cutting down your existing boom as was suggested earlier if the outhaul will work with your sail, or..... starting from scratch if you want to get back to the 9ft boom. It's only $$$$$.
Stay tuned.

 

[Syntonos]

Yamaha 25mkII Boom Specs.

Ok here we go. Hope all the pics upload ok.
The mkII boom is 9.0ft OAL. As you can see the end castings are pretty elaborate. The gooseneck on my boat is pretty worn prompting my re-working the systems. The boom is rigged as illustrated in the manual, for 2 reef points. My new sails will have only the lower reef points. I use a "boomkicker" boom strut. works great with no problems from the fiberglass rods. I'll be rearranging the outhaul system as the strut and outhaul exit conflict with one another. I did a quick search of spar sections. Unfortunately none of the sites showed the dimensions used, I'm sure it's out there. In fact a cruise through my local salvage chandlery turned up two usable spars so it must be a standard extrusion. Sorry- I bought the better one for my project. Mine shown in the pics will be available cheap, less fittings, after I'm done with the project if any one needs it.

I've also included the sail plan I'll be going to - Ullman full hoist 115% headsail, reworked mainsail with a slight raise of the boom. It'll be interesting to see how it all comes out.

cheers

 

[alturaam]

Excellent, Syntonos. Thanks for postings those pics! You provide an excellent blue print for a sail plan. I talked to one of the local rigging shops and they can cut my boom and move fittings. WIll do this next week. Hopefully, they can transfer the fittings without any problem. My original edge of mast to tip of boom measurement was 9'9", I will ask the shop to lop 6" off my boom.


Questions: 1) What is your measurement from top of the mast to the top edge of the boom after you raised the boom? I have a top of mast to top edge of boom measurement of 29'5" on an overall mast to deck measurement of 31'10".

2) Are you sticking to your furling system with your new 115% headsail?

3) That boomkicker arrangement is nice. Was it scavenged from somewhere?

You were right about your boom being turned in to Swiss cheese. There were a lot of holes in that pic.

 

[Syntonos]

Y25 mast ect.

? 1) My manual shows the mast at 30ft 7inches. My boom is at 28'2" and 30'2" to deck. I've heard of a Tall Rig. Maui Pro Sailing website shows the rig at 32' 7" with the boom at 29'8"
Perhaps that is what you have?

? 2) Boom Kicker-- No, they are available for about $200 (ouch) from boomkicker.com. I believe the model # is O750

? 3) I'll be keeping the furler . It's a Furlex s100 dual foil. Selden sells it.

Yeah the boom has been re arrange quite a few times over it's 35 years. Still works fine.
The cut of my main sail had a long leech that allowed the boom to droop down (not parallel to deck) I guess that was the hot tip back in the days of IOR racing. The new sail will raise the end of the boom out of the cockpit. gooseneck will be about the same height

 

[alturaam]

Hi Syntonos,

These are the dimensions for all variants Yam 25 boats. I've also seen the Mauri Pro dimensions.

YAMAHA 25 31.8 9.8 27.9 9.0
YAMAHA 25 Mk 2 30.5 9.8 27.9 9.0
YAMAHA 25 Mk 2 Tall rig 32.8 9.8 29.9 9.2
YAMAHA 25-2 32.8 9.8 29.9 9.2 32.8 9.8
YAMAHA 25-2 SD 32.8 9.8 29.9 9.2 32.8 9.8

All my dimensions are the same as the plain yamaha 25 except for one, the top of mast to top edge of boom measurement, where I am at 29'10", which is the same for all teh other variants. So what do I have? I think I have the first variant where the owner used a main for the last three variants. This is fine by me. I have already asked for quotes from three sailmakers for a main and have fuond a shop to cut my boom. I also thought of raising the boom, but I think intuitively that would reduce righting moment, which I am not keen on especially when I solo most of the time. What I do want with a new main (and eventually a new furling jib) is a reduction in weather helm. I have too much of it in my opinion. I redeuce it somehwat when I use my 120% headsail and I may opt for a 115% like you. Thanks for the data on teh roller furler. I will look that up.

Incidentally, after months of searching old threads, i was able to locate parts for my original manual bilge pump, a Henderson Chimp MkI from a group called Gael Force Marine in Scotland. All I had left were a handle, the main housing and the hexagonal frame for the diaphragm. I was able to order three kits to replace the diaphragm, inner clamp, the intake and outlfow valves as well. With shipping and all, it is about as expensive as a new pump but with this, I don't have to modify holes or mounts on the boat. I assembled it last night and will install this weekend. I sailed all season without a bilge pump.

? 1) My manual shows the mast at 30ft 7inches. My boom is at 28'2" and 30'2" to deck. I've heard of a Tall Rig. Maui Pro Sailing website shows the rig at 32' 7" with the boom at 29'8"
Perhaps that is what you have?

? 2) Boom Kicker-- No, they are available for about $200 (ouch) from boomkicker.com. I believe the model # is O750

? 3) I'll be keeping the furler . It's a Furlex s100 dual foil. Selden sells it.

Yeah the boom has been re arrange quite a few times over it's 35 years. Still works fine.
The cut of my main sail had a long leech that allowed the boom to droop down (not parallel to deck) I guess that was the hot tip back in the days of IOR racing. The new sail will raise the end of the boom out of the cockpit. gooseneck will be about the same height