What do you think of the not so new anymore wave shape/C shape booms? I personally hate them and don’t really get the benefits that the “ C “shape supposedly provides. It’s almost impossible to find a small/wave size regular shape booms anymore though. From what I’m seeing online the small Chinook Pro carbon is maybe the closest you can get to a “regular “ shape in those sizes. The arms of my current aluminium rdm boom have started to bend again and replacing it with the Chinook Pro moves to the top of my windsurfing shopping list.

C shape and Regular shape

i love the new-school bend, but not everybody loves them. they are primarily beneficial for sailors who use an overhand grip as the straight section on your front hand is more ergonomic for this type of grip. freestyle and wave sailors tend to prefer this boom shape. if you sail with an underhand grip, you may be more comfortable with the traditional boom outline.

If you just grab your boom from your car and hold onto it with both hands overhand... then keep inching your front hand forward toward the mast, you will feel it harder to keep your front arm straight the more the boom arm bends back toward the mast.

Dave Dominy of Streamlined was the first company to use this new school shape for wave booms. You even see it to some extent on slalom booms now. the idea is to get the area where you are holding onto the boom as straight as possible so your wrist doesn't have to bend inward using an overhand grip. Not all of these new-school booms are the same though. Your Unifiber diagram shows the boom bending back toward the mast soon after the harness lines. The Streamlined boom stays straight for quite awhile, and the North/Duotone booms extend straight even a bit further forward (my personal wave/freestyle booms). The Aeron OEM booms bend back toward the mast much sooner.

If you're looking for a more traditional shape, you can look at Maui Sails & NP carbon booms.

I've attached a picture of two booms. One is the Duotone EPX (Aeron OEM) and the other is a Duotone Platinum. You can see the difference in the front hand portions of the booms.

I just bought and used for the first time North Silver boom which has that new-school shape. I switch back and forth under- and over- hand grip depending on what I'm doing-- schlogging, cruising, jibing, and it is definitely more comfortable for the overhand grip, no effect on my underhand grip, but that's probably because that's when I'm trying to relax and use as little effort as possible, just cruising with as much weight as possible on harness.

Thanks, Kevin, for pointing me out the core issue I have with the new shape booms. I definitely use predominantly under-hand for cruising and the straight arm is making it uncomfortable. The last time I used that boom I kept switching between over and under-hand and contributed the discomfort to arm fatigue while the reason has been the boom shape. There is also a difference when flipping the sail because my hand can’t slide close to the mast, it stops at the bend. I don’t like that too.
You’re right about the Maui Sails booms-can’t get more traditional then that. Unfortunately the grip diameter is also traditional and 30 mm is too wide for my smallish hands. I think I’ll stick with Chinook for now.

I have to agree with Ady for once on this one! When freeriding back and forth, front under-hand (supination) is more comfortable (both forearm bones are parallel). It's closer to a neutral relaxed stance for the arm. In a front hand supination grip, the thumb points outward and the fingers naturally will conform to the curvature of a regular boom while the hand stays relatively aligned with the forearm. The only moment when C-Shape boom wouldn't be an issue to the freerider/slalom rider is when sailing a big rig (like a 8.0 or above) and where the harness line are so far back that the front hand would finds its place on the straight section far away from the bend anyway. But I doubt they make C-shape booms to rig on large sails anyway, right?

To share an experience similar to Ady's with his hand stuck at the bend on C-shape booms, it involves a regular shaped North Sail 190-250 Slalom boom I got last year to rig a 9.4 and 8.5. I like how rigid and stable the rig is with that boom, but starting at 30mm, the diameter grows substantially thicker near the boom clip. Every time I jibe with that boom, the progressively extra thick section slows down my hand as I slide it right before the sail flip. Annoying.
In addition, the tail of the boom rides over the main section making it rigid (nice) but also making it thicker and somehwat unbalanced because heavier towards the clue. The extra weight there takes some getting used to during jibes (pulls the clue down) and presents the disadvantage of being even more of a pain to uphaul - which prompted me to learn how to waterstart my 9.4...
While the Chinook Pro1 Carbon 200-260 weighs a few more grams than the North/Duotone, I bet the Chinook is more balanced but probably a tad less rigid.

Ady wrote:
One thing the windsurfing industry does that I absolutely can't stand is that most companies when they quote boom "grip size" are really using the tube OD measurement without EVA grip. Whenever I get new booms, I break out the calipers. Anyone have a Chinook RDG carbon they want to measure? Anyway, I'll post some results here. Readings are a loose average in the main grip area. Tubes are usually a bit out of round, so I try to find a measurement that I feel roughly represents the true grip size. The +/- on these measurements along the boom are quite large. Actual measurements are listed with the spec grip size in parentheses. EVA grip is usually 1.5-2.0mm thick.

measurements from 2017:
Streamlined Carbon Wave 140-190: 29.4mm (29mm)
Goya Super Skinny Carbon 140-190 (Aeron OEM): 28.45mm (24.5mm)
Maui Sails Carbon Wave 140-200: 30.1mm (30mm)
Chinook Pro-1 Carbon 135-185: 30.0-32.5mm (28mm) big variation here b/w front hand and back hand. bare tube near adjustment collars is ~29mm (also not newest version of this boom)

measurements from 2019
Duotone EPX Carbon 140-190 (Aeron OEM): 27.9mm (24.5mm)
Duotone Platinum Carbon Mega Slim 140-180: 26.6mm (24.0mm)
Duotone Platinum Carbon 140-190: 29.6mm (27.5mm)

www.instagram.com/p/BRrirSxFB85/

An update on my North Silver boom, which I thought was a great deal (<$200) on closeout now that North has become Duotone. This alloy boom turns out to have the worst sand sticking I have ever had, but I have never had a boom with this problem ever before. The last time it got stuck I had to pound the extension with a hammer with almost all my strength to loosen it a fraction of an inch every pound, it never loosened until it was all the way out, maybe 50-75 hard blows with hammer. I have decided to use it with only one sail, the only sail that I can't fit another boom on, and tape the joints to keep sand out. North also put a hole in the collar where sand can get in. All the markings have worn off so I put sharpie markings on the tubes. I wonder if the Duotone silver boom has this problem, but they have changed the boom extension tubes to an oblong shape (horizontal dimension wider).

Now I have matching taped booms, a North with tape covering the extension joints, and a carbon Chinook with tape around the collars to keep the pins engaged. Have had to adjust boom length on the beach once so far, a pain, but the electricians tape seems to tolerate being reused just fine.

I believe that I’ve found what I’ve been looking for in a wave boom. This skinny SX10 from Simmer has the classic shape that I like, no “ new school” nonsense. It was praised in “Surf” comparison test for stiffness, lightness, quality and ability to accommodate sails with more shape. The holes in the tail peace are moulded instead of drilled and it’s the only one having a 60 cm!! extension range on top of being one of the widest . Diameter including grip is 28 mm which is slightly thicker then most skinny booms but still slimmer then the 32 mm regular booms. I’m so tired of dealing with bent, sticky aluminum booms that I think that would be my next purchase/almost paid off the last mast that I bought/.

Ady, Simmer also makes the same(ish) boom with a smaller grip: SX10 Carbon Slim if you wanted to go for an even smaller tube 24.5mm. All these quoted "grip sizes" are raw tube sizes without grip which is ~1.5-2.0mm thick, so add 3-4mm. Some companies can have very thin grip in the ~1.0mm thickness.

The Simmer SX10 Carbon boom is an OEM boom, and I believe it to be different than the Aeron and Aeron-made booms. In wave sizes, I believe Point-7, Simmer, and now S2Maui are offering this boom. I will be carrying the S2Maui Wave 140-200 slim, but my first ones don't arrive until March, and I haven actually seen one in person. Would be happy provide feedback when I actually get to sail on one.

I just sent a message to Casey Hauser to see if he and BMP can give any feedback on the boom. Do you have a link/copy of the German boom test?

Also, can you remind me which new school boom you were using that you didn't like? There's sometimes an adjustment period, and some people have to go with longer lines to accommodate the slightly different body position of the new school booms. I think you said you sail with a front hand underhand grip which is better suited to a more traditional boom bend. However, if you're getting into freestyle or waves and/or jibe w/ an overhand grip, that's when the new school bends really shine.

Kevin Kan wrote:

That’s the same boom I’m talking about the slim one with 24.5 mm tube diameter. The Germans measured the outside diameter which was 28 mm in the test. Surf have a website but they don’t post test details unless you pay so here is a screenshot from my subscription application. I have made up my mind so I don’t want to start a discussion so I’ll leave it at that.

does the Surf Magazine app have translation to English?

Do they also talk about which booms are the same or different? The Point-7 looks to be different than the Simmer from the picture, or maybe they are different tube sizes?

Always interested to see which booms are good.

No English edition unfortunately as far as I know. This comparison test is about 13 skinny/slim/rdm top model booms and outside/real diameter, weight and stiffness/against 35 kg weight/ are measured in addition to on the water/practice test. Specific details are highlighted like tail width and how well clams work when sand is involved etc. For example the Chinook and Severne are the lightest of the bunch but the Chinook is also the softest. It bends by 3 cm when the 35 kgs are applied compared to only 0.5 cm for the Point 7 which is also the heaviest and the cheapest . Not necessarily good or bad but rather helping you choose what suits you best. Point 7 and Severne are RDM masts only heads, so you must take that into account and some like me would prefer a wider tails for sails with deeper profile and some /like you / would prefer the opposite. Also some booms have better working clamps and some have plastic tail end protectors while some don’t. Goya has the new school front but also one of the widest tails. Severne has the best ratio between weight, stiffness and small diameter but is the narrowest, rdm only and lacks tail protectors. Price difference are significant as well.