Gennaker Bowsprits

Gennaker BowSprits are so popular today due to the simplified spinnaker handling. No more spinnaker poles.

Many Sailboats these days have some sort of Asymetrical Spinnaker, Gennaker or Cruising Spinnaker. These type of sails need to be tacked down forward of the stem or bow to get as far away from the mainsail to set properly. Otherwise asymmetrical sails are very simple to use.

Many modern racing sailboats have Sprits, spinnaker poles that are built into the hull, and are extended out for use. J/Boats are the one brand that has made this very popular. The J105 class was at the forefront using sprits back in the 90’s.

But if you don’t have one, how can you retrofit one?

J/105 courtesy JBoats
J/105 courtesy JBoats

 

There are several Companies who make kits to achieve this. Selden, Sparcraft and Forte Carbon make complete kits that can be installed on the foredeck. They consist of the sprit itself and forward and aft mounts.

These poles are designed for soft luff sails. A code zero is a hard luff sail and has considerable more luff tension to make it set properly.

BowSprit benefits

Having a sprit increases the performance of the asymmetrical spinnaker so much, its possible to have a sail smaller in area and still perform better.

Benefits: • Gennaker has more clear air • Helps gybing as tack is further away from bow • Simple and efficient Gennaker handling • Improves Gennaker performance

Another benefit is anchoring; being able to pull your anchor chain away from the bow. Hang a deflecting block from the sprit and pull the anchor chain forward.

Mounting a Bow sprit

There are several things to look out for when installing one of these Sprit Kits. First is where the sprit will live and then you need to look at control lines.

Sprit Length; Carbon Sprits use a 1 to 1 ratio of supported length to free length, while alloy Sprits need 2 to 1. Alloy poles require a longer supported length as Alloy flexes more than carbon. So if your looking for the sprit to extent 6 feet from the bow you will need a 12 foot Pole in Carbon or 18 feet in alloy.

Layout; Forte recommends getting a piece of PVC tube something that can mimic the Sprit diameter and length and place it on the deck. Place your mockup tube on the deck with it retracted and then extended. Then you can experiment with places to install the mounts.

Tackline; The next thing you need to plan is the tack line for the sail. There are 3 options; having the line run through the pole or above or having a loop on the end to shackle the tack down. Both the Selden and the Sparcraft Sprits are designed with the tackline running through the Sprit and exiting at the aft end. The Forte Sprit has a loop at the forward end and the tackline runs over the top of the Sprit.

With the tackline running above the pole, I have used the windlass as a cleat. The windlass works great and all you need to do is check the run from the forward end of the sprit to the windlass. If not then you can run the tackline further aft.

Selden BowSprit

Manufacturers Description

Selden’s extendable gennaker bowsprit is sold as a kit for deck mounting. Just fit the two stainless steel pad eyes to the deck in line with the bow bracket. This bracket is a stainless ring with a low friction polyamide inner lining through which the bowsprit slides into the “active” position. After the Gennaker is doused, the bowsprit can slide back and be secured to the aft eye. If required, it can be quickly removed and stowed securely below.

The Gennaker tackline (supplied separately) runs through the bowsprit, entering and leaving via well rounded holes, and then aft to the cockpit. An alternative is to fit an external tack block at the outboard end.

Selden web page

Forte Carbon Sprit Kit


The easy-to-install Forte Carbon Sprit Kit includes everything you need: a beautiful clear painted carbon fiber sprit, your choice of easy-to-mount deck hardware and a robust outboard end fitting.

Forte offers four sprit kit sizes to accommodate your boat. The carbon fiber sprit tube will actually be engineered and built to your specific requirements. Because of this, the OD of the tube is not set in stone; the laminate (wall thickness) may be a little thicker for heavier boats or boats carrying more sail area

Forte Manufacturers Description

All of our Sprit Kits come with a Forward Mount and an Aft Mount. The Forward mount is a “saddle” style mount which is machined from a Starboard block and includes threaded stainless rods and mounting hardware to easily secure the block to the deck. The idea behind the starboard block is that it is relatively easy to work with if you need to adjust the height or cut a curve into the bottom. You can see in the picture below the saddle mount was cut to fit over the tow rail.

Forward mount and Aft mount
Forward mount and Aft mount

The Aft mount can be your choice of saddle mount (identical to the forward saddle mount), or a removable deck eye. The removable deck eye screws into a plate that is mounted in/on the deck. The aft end of the sprit has a machined receiver block that fits over and pins to the removable deck eye. This allows for a total clean deck when the pole and deck eye are removed.

Forte Carbon Sprits

Small – for boats from 15’ to 27’ long 2.25” ID, estimated OD 2.7” Maximum sprit length = 9’

Large – for boats from 34’ to 40’ long 3.9” ID, estimate OD 4.4” Maximum sprit length = 12′

Medium – for boats from 27’ to 34’ long 3.375” ID, estimated OD 3.8” Maximum sprit length = 12’

Extra-Large – for boats larger than 40’ 4.5″ or 5.0″ ID, Estimated OD 5” or 5.5” Maximum sprit length 14’