LoopBlock-QA_main_black
PUMA's il mostro, VO70 — Billy Black photo

T2™ All-Composite, No Metal

Harken Carbo T2 Soft-Attach Block

T2 blocks are the first blocks made entirely of high-strength composite material—no shackles, fasteners, or rivets. This tough new line of soft-attach Carbos is our lightest and will never corrode.

One style T2 uses a loop, the other a length of line. Both route the attachment line through the block head and sheave, reducing load on the sideplates, acting as a safety backup for your system.

Soft-Attach Blocks Q&A

6/13/2012

Why are so many people switching to soft attachments? 
Racers like soft attachments because they are much, much lighter than shackles and metal attachments. They won't scratch or ding your deck and they are flexible, which means they align almost perfectly for a fair lead. You can mount them in a wider variety of places like booms and they won't bang against your boat (or your head!). However, soft attachments require regular attention to ensure they are in good condition. You should only consider using them if you frequently inspect your equipment or have a professionally maintained boat.

What Harken equipment uses soft attachments?
Harken soft attachment block typesHarken makes Carbo T2™ blocks for small boats in 29, 40, and 57 mm sizes. Black Magic® Loop Blocks are available for larger boats and high-load applications. The Black Magic® Airblock® line has a series of Loop blocks in 57, 75, 100, and 125 mm sizes. 

Additionally, Harken makes a line of 98%-efficient TTR blocks with maximum working loads of up to 8,000 kg (17,641 lb) as well as high-load snatch blocks for up to 12 tons or 12,000 kg (26,460 lb ). Finally, several traveler and Grand Prix athwartships systems feature soft attachments for control blocks.

Why would I use loops (continuous circular lashings) instead of standard lashings?
Loop block dead-ended on padeyeLoops offer a quick, clean, and secure attachment with no tying or splicing involved. There are no messy knots that could weaken the line or come loose, and most attachment methods can be done safely without a professional rigger. Professional loop-style lashings are usually extremely strong as well—the Yale Cordage "LOUPS™" sold by Harken are carefully designed with multiple coils of Dyneema® and an abrasion-and UV-resistant Spectra® cover. They are pre-stretched and steamed so the multiple laps evenly share the load to provide maximum strength.

Patented Harken Loop blocks take advantage of loop-style lashings with an optional dead-end post which lets you use a loop to tie around padeyes and other closed bails. With other blocks, you would have to install the loop by splicing the line around the bail.

Can I use my own soft attachments?
Yes, but any rigging of soft attachments should be done by a very competent rigger who is keenly aware of fiber strengths and their applications. Published Maximum Working Loads assume you are using a soft attachment that is appropriate for the block and the application, that it is tied properly, and that its breaking load exceeds the breaking load of the block.

Can I use circular loop lashings with any soft attachment block? 
No, loops should only be used with blocks designed for them.

Do I really need to use the secondary lashing on the head of Loop blocks?
Loop block head lashingYes. The head lashing is critical for safety as it keeps the block aligned correctly and prevents it from capsizing during intermittent loading. The distance from the sheave to the head lashing ensures the block will not flip the line off the sheave, leaving the sheet to ride on the primary lashing instead of the sheave—this is why you have to be careful with rounder blocks that don't have prominent heads.

Can I use any secure knot to lash Loop blocks and T2s to my boat?
Definitely not. Loop or lashing strengths vary dramatically depending on how they are configured, and the tight bends in most knots weaken lines considerably. Soft attachments must be tied by a very competent rigger who is keenly aware of fiber strengths and their applications. Harken sells Yale Cordage LOUPS™ for Black Magic® Loop Blocks which are carefully designed with multiple laps of high strength Dyneema® and an abrasion- and UV-resistant Spectra® cover. They are also pre-stretched and steamed so the multiple laps evenly share the load to provide maximum strength. The line included with T2™ blocks is similarly tailored for rigging applications.

LOUP™ tracersWhen should soft attachments be replaced?
Weather, chafing, stress, and UV light damage soft attachments over time. Look for signs of wear, abrasion, or discoloration. Yale Cordage LOUPS™ sold through Harken have colored UV-sensitive tracers that fade to indicate significant exposure.

Are there any T2 Carbo blocks with beckets? 
The becket does not come standard as part of the molded block. However, you can make a becket by passing the line through the mouth of the block and making two becket loops. Detailed instructions come with your T2.

TTR rigged as spriddleCan blocks be tied together to make spriddles or fiddles?
We don't recommend tying blocks together because you are doubling the load on the block closest to the attachment point, but it is possible to configure something very similar to a traditional spriddle or fiddle (fiddles are like spriddles except the smaller sheave has a lower Maximum Working Load). Two blocks can be used in conjunction, but you should not put the entire load on a single block. Instead, make sure the lashing takes all the load by using a common attachment point for two lashings.

Where can I find multi-sheave soft-attachment blocks?
The Black Magic line includes 75 and 100 mm straphead spriddles and a 75 mm straphead double. Experienced riggers can also make spriddles from single T2s or Black Magic® Loop Blocks.

Can I take out the headpost of my normal block and use it as a soft-attachment block?
No—this is very dangerous. Blocks with shackle headposts are designed for different load placements. They also may have sharp edges and other wear points that can cut into your soft attachment line.

 Loop block vs. StrapheadHow can I tell if I have a straphead block or a Loop Block?
Black Magic® Loop Blocks have soft attachments running through the center of the sheave while straphead blocks have webbing attachments fastened to the head. Loop blocks are lighter because they don't need as much load-bearing material in the head.

Are Loop and straphead blocks interchangeable?
Definitely not. Running a soft attachment through the head of a Loop block instead of the center of the sheave is risky and could result in block failure, even when loads are less than the Maximum Working Load. Loop blocks have less material in the head because the sheave is designed to be the primary load-bearing component.

Doing the reverse—running soft attachments through the center of the sheave of a straphead block—can also cause problems. The edges are not appropriately radiused for this use and could chafe or cut your soft attachment.

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