Anchors and ladders for a 12' RIB

[Cthippo]

Now that my RIB is holding air finally and I think I have the correct fittings for the fuel system, it's time to start thinking about actually using it for diving. I'm curious what size and type of anchor people use and also what you use for getting into the boat. Would operating and diving solo from the boat change your answers any?

The common Danforth anchor seems awkward and pointy for handling in a small inflatable boat, so I am thinking of something more like a mushroom anchor. A 30 lb mushroom would take up a fairly small amount of space and shouldn't go anywhere unless there is a hurricane blowing topside.

 

[dfcliff]

Now that my RIB is holding air finally and I think I have the correct fittings for the fuel system, it's time to start thinking about actually using it for diving. I'm curious what size and type of anchor people use and also what you use for getting into the boat. Would operating and diving solo from the boat change your answers any?

The common Danforth anchor seems awkward and pointy for handling in a small inflatable boat, so I am thinking of something more like a mushroom anchor. A 30 lb mushroom would take up a fairly small amount of space and shouldn't go anywhere unless there is a hurricane blowing topside.

I wouldn't trust a mushroom anchor in anything but the lightest of winds and currents. Depending on where you are diving and if anyone will be in the boat to monitor if the anchor starts dragging, I would err on the side of more holding power than you think you will ever need.

How to Choose an Anchor

www.bassproboatingcenters.com

 

[Jonn]

If there’s someone on the boat they might as well drift as they watch your bubbles. If it’s an empty boat I’d want to plant the anchor myself, or better yet chain it right to a wreck or something.
I’ve got plenty of experience climbing into RIBs and there’s no really great way. Usually simpler to hand up your weights and rig (separately please!) and just crawl over the pontoon. Suspect a ladder would be more trouble than it’s worth on such a small vessel.

 

[Boarderguy]

@dfcliff
A lot of our bottom composition here in the Puget Sound is mud and muck. You can find rocky bottoms but those aren't as easily accessed. A mushroom may do well for a rib here.

 

[Alaskan Scuba Dude]

 

[grf88]

Ideal boat design for a solo diver

At the risk of stating the obvious, and this really applies to all boats. make sure all the shackles used for the anchor, chain and line (rode for you purists) are tightened and wired so they cannot vibrate loose. Inspect all component regularly. I was once on a charter that suddenly started...

scubaboard.com

Follow link above for suitable ladder.

 

[GiraffeMarineSalvage]

I agree on not needing a ladder, more trouble than it's worth on that size inflatable..
Suitably sized Spade and Manta are the two designs you can really trust, Danforth is excellent in soft bottom types as long as there is only a single direction of pull (BUT don't trust it to reset if tide or wind makes direction of pull change dramatically...)
I also personally like a drastically oversized Bruce anchor (35 lb!) for most dinghy anchoring simply because of the lack of pointiness and ability to reduce scope more than otherwise prudent...
I would not personally trust the typical mushroom or grapple style small anchors..
I'm also a fan of a short length of chain between anchor and line, and proper scope is extremely important for any anchor to properly work, and for tides/swell needs to be factored into that calculation.
7:1 allows about as much holding as anchor is capable of, but 5:1 and depending on circumstances 3:1 can be adequate... A massively oversized anchor is the only way I think it may be reasonable to go less than 3:1.
P.S. I realize the above advice may seem "excessive" since "oftentimes" one can get by with less, and sometimes much less but it's priceless to know if conditions change on a dive my dinghy will be exactly where I left it...

 

[Johnoly]

I'm also a fan of a short length of chain between anchor and line, and proper scope is extremely important for any anchor to properly work

This is the best advice. Even in an inflatable it doesn't matter if the anchor has spikes or mushrooms. It's going to move after 45 mins of tiny tugs on your boat rope from passing ripple wave action without the proper length & size of chain.

 

[johndiver999]

I think I would find a very small danforth, add more chain than you think you need and keep it all in a 5 gallon bucket on the boat. You will be setting the anchor when you first descend. Diving from an unattended (and inflatable) boat at a location that does not afford you the opportunity to swim home, is something that I would try to avoid.

 

[GiraffeMarineSalvage]

Also one side note on including a length of chain: seizing shackles with stainless steel wire is highly recommended. Even if you're only going to be anchored a short time / single direction of pull in mellow conditions it's simply the right way to do it and priceless peace of mind..