Choosing & Setting Up a Raft Bimini

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Shade can be a valuable commodity on the river. Umbrellas work, but nothing beats a good bimini.

Choosing a Bimini
As for deciding what bimini is right for you, there’s a wide variety of pricing & quality options available. Keep in mind, you get what you pay for and your level of care will affect longevity. Some people can make a budget bimini last a few years, while other budget biminis may not survive one gusty afternoon.

Plastic vs stainless steel
Cheaper biminis often have plastic mounts and fittings, which can dictate the function & overall life.

Poles
These come in aluminums and stainless. Stainless poles are more expensive and better in a strong wind. That said, if they’re kept clean and sand free, the more budget friendly aluminum poles work just fine.

Fabric
You can get biminis with paper thin fabric and you can get biminis with super thick Sunbrella. You should expect that the better the fabric, the longer the life and durability and, the better the bimini should be able to handle the wind and sun.

Sizing and a little terminology
Most rafts will either use a 3 bow 6’ length or a 4 bow 8’ length bimini. Both types tend to be 54”-60” in height, measured off the raft frame plane.
The 3 bow 6’ length biminis are usually the best fit for rafts 14’ and smaller, while the 4 bow 8’ length is usually the best fit for 15’-18’ rafts.
The other measurement you’ll need is the width between where you are mounting the bimini. For a 16’ raft that is 78” wide, you’ll want a 4 bow bimini that is 73”-78” wide. We’ll get more into this measurement later, in the oar towers section.

Set Up Tips
Setting up a bimini is fairly easy. Dialing it in has its nuances. There are a few details, which tend to interrelate, that you’ll want to pay attention to.

What part of the raft you are trying to shade?
To get a rough idea of where shade may land, first, determine where the feet of your bimini will be mounted. Then, put a tape measure, which reflects the middle of your bimini, at these spots. So, a 36” tape for a 6 foot, and a 48” tape for an 8 foot. The circle you can make with your tape measure is the area where the bimini most likely will provide shade.

bimini to oar tower spacing

bimini to oar tower spacing

Oar towers & Bimini Set Up

When the bimini is up, for the upright bars to not interfere with rowing, the feet need to be at least 12” (fore or aft) from the oar tower. Different styles of oar towers will dictate where you can mount your bimini, and possibly what width bimini you can mount on your raft.
With speed rail style oar towers, that are on the inside of the raft tube, or other deck mounted oar towers, your only option may be to mount your bimini aft of your oar towers. Or, you may have to get a bimini that’s not as wide as your frame, so the bimini bars can lay inboard of your oar towers.
We have found the new style NRS oar towers work well with biminis set up in the reversed position. With the addition of a riser block, one can mount the bimini on the furthest out frame bar, which makes for a cleaner set up, allowing for walking & more room to rig items on your side decks. We make riser blocks out of 1” square tube, but it’s possible to use other things like Trex or a chunk of hardwood. You’ll need longer machine screws to mount the foot.

standard set up

Standard or Reversed Set Up?

Biminis have 2 bars that come down close to the mounting foot. One pole ends just short of the foot.

The standard set up is with the shorter bar on top when the bimini is stowed. This is best used when the bimini is mounted behind the oar towers & allows for easy set up & dropping of the bimini. It also shades the rower’s position well. When folded down and stowed, this type of set up tends to fall further back, either on the back of your gear pile or on the raft tube itself. When the bimini is up, shipping your oars isn’t easy & shade tends to not cast over the front of the raft.

reversed set up with riser block

The reversed set up is with the shorter bar on the bottom when the bimini is stowed. This is best used when the bimini is mounted in front of the oar towers. With this set up you’ll have to ship your oars when setting up and dropping the bimini. Since this set up is more forward, it tends to keep the front of the raft, passengers, better shaded, and you’ll need to be careful about how it lays down on your raft and gear pile. This reversed set up can be challenging with some oar tower styles.

bimini mount kit

Mounting Options
There are a variety of ways to mount a bimini to your raft frame.
One way, that’s both adjustable and functional, is to mount the bimini foot to a chunk of 2x4 long enough (6”-14”) to strap down to your frame. If you aren’t exactly sure where you want to permanently mount your bimini, this is a simple & non-committal way to try out different locations on your boat. The 2x4 also acts as a riser block.
Another method for mounting your bimini is to screw the bimini feet to the raft frame’s decks. This works but can create a potential toe stubbing & tripping hazard.
You can also use a sliding track mount kit. The concept is a good idea, but most people who have these tend to get their biminis set and then never adjust them again. If that’s the case, it’s probably better to just use a 2x4 block until you get your mounting location dialed in.
Lastly you could use the machined mount kits, available for both 1.25” & 1.5” pipe, that River Sombrero makes. These work great, by allowing you to put the bimini feet further out on your frame.

Passenger comfort, safety, and your gear load

For figuring out how your bimini will stow when it’s down, the 3 bow 6’ length biminis fold down 64” from the foot & the 4 bow 8’ length biminis fold down 74” from the foot. Ideally, you’ll want to figure how to make space for your bimini to stow as flush as you can to the frame. Some people let the bimini fall forward to the bow and stow it there. That’s an option, but we’ve found this gets in the way when loading, unloading, and can also be a safety hazard.
This may be obvious, but clearly there is a line in running riffles & small rapids where it just makes sense, for safety’s sake, to put your bimini down. Your boat, your call. A bimini just folded down on a raft frame can still make for some entrapment hazards. For rapids that pose significant consequences, it’s wise to stow the bimini in its boot and/or strap it down & put some bags over it, to make it less likely that something could get between the bimini bars and the frame.

Well, that concludes Raft Biminis 101. We realize this blog was a long one, but we hope it helps you with making some of the decisions that need to be made when it comes to choosing and setting up a bimini on your raft.