45' Leopard Catamaran Delta anchor power set rpms

[ks2cs2]

I own a 2021 Leopard 45 catamaran (lots of windage) with two (2) 45-hp Yanmars w/ fixed blade props using a 55-lb Delta anchor and all chain. I am looking for recommended rpm's to power set the anchor and have not been able to find power set rpm recommendations for catamarans in my searching (almost all monohulls). To eliminate a variable, let's assume sand bottom (similar to Bahamas, BVI, etc.). I typically drop anchor, slowly pay out chain to ~3:1 scope, engage reverse to allow it to grab/prelim set, then pay out chain to 5:1, engage chain stopper, and then slowly power up to 1500rpm and hold for 30-secs. However, recently in BVI (off Prickly Pear Island in sand and a little grass), I did this and, because we expected high winds, after slowly going to 1500rpms, throttled up to 1800rpm and the anchor pulled out (fairly dramatically). Now, perhaps we were in some grass or the anchor got fouled somehow but I am looking for guidance on rpm's with a catamaran (2 engines) to power set the anchor. Is 1800rpms with twin engines too high?? Does anybody have any information on bollard pulls for catamarans?

BTW - changing out the anchor setup is not a variable and cannot be changed due to this is the standard Moorings setup for the new Leopard 45's.

[ks2cs2]

I forgot to add that we had increased scope to 7:1 before we increased the rpms to 1800.

[Thumbs Up]

It is better to let the anchor settle in first for 1/2 hour or so in those kinds of bottoms (soft sand or silt with grass). A well set anchor should withstand a pull at any RPM that you can deliver. Then you should dive the anchor and check it or at the very least get a visual confirmation that you are set and not just hooked to some debris. With a deep sand bottom, you can power set right away. I have never heard of a specified RPM to set an anchor. I suppose there is a point where too much throttle would decrease the pull due to excess cavitation (the same way a car wheel loses traction and starts to spin).

[BillKny]

With props such as you have, "bollard pull" is typically quite a bit less that 1000lbs at full throttle. Certainly WAY less than I'd want my anchor to hold.

If your anchor can't hold full throttle pull, at full scope, it is either not set properly, OR, in a bad patch of bottom, OR too small, or some combination of those things.

I know you do not want to hear it, but a 55lb Delta is MUCH too small for a cat of that size. 55KG would be better. Hopefully you have a typo there. If not, please always anchor far downwind from me...

If a 55 POUND anchor is really the "standard Moorings setup", god help us all....

[smj]

So Leopard designed the boat so it would only accept a Delta anchor or you have a charter arrangement that only allows a Delta anchor. My first and only thought would be to replace the Delta with a New Gen type anchor. Deltas were great in their time but the New Gens are so much better

[ks2cs2]

Thanks for the quick responses! To answer your questions...The 55-lb (25kg) Delta DTX is standard on all Leopard 45's unless it is changed out by the owner at the factory; therefore it is standard equipment on all M4500's with The Moorings (please see attached excerpt from the Leopard website). I would love to change mine out for bigger/better, but cannot as it is in The Moorings program for awhile. I suspect it was fouled when I took it up to 1800rpm as I have set it numerous times at 1500-rpm and it set well in clean sand and was rock solid. So, it looks like I will make do for a bit... and set the secondary when the winds are expected to kick up!

[ks2cs2]

I would still like to know what reverse rpms other catamaran owners use to power set their anchors...

[HighTemp]

Exact same ground tackle setup on our Saona 47.

After we dig in, we set both throttles at 1500 RPM.

[Jenta]

Lagoon 440 with 54hp
J-Prop SD83 feathering props (reverse has very good power)

We upgraded last year to a Mantus 85 M1

I almost always dive my anchor if I can and in sandy anchorages in Bahamas would usually find that if I backed down at around 1500-1800 RPM I had a great set with the anchor nicely buried. If I backed down to 2000 RPM for a minute I would pull back maybe an additional foot or so and all I would see above the sand is some of the hoop.
To give you an idea of the comparison, last year we were at Little San Salvador in Bahamas and rode out a wind reversal that went from light wind from the South to 45+ knots from the North in less than a minute.
Checking it out later, the anchor rotated and reset either in place or maybe 3-5 feet. The hoop of the anchor was buried no more than a 1500-1800 RPM backdown would have done. So my guess is that in that situation my 2000 RPM backdown was more pull than 45 knots of wind. (No math or theoretical physics. Just an observation)

In the river off the Coast Guard station in Charleston however, as others have noted - you can't usually back down unless you let the anchor settle. I'm guessing it is just too silty and we learned that the hard way a couple years ago with the 70ish pound delta style anchor we had.
What ended up working there was a very light "pre-set" at more or less idle. Followed up much later with a modest backing at 1200 RPM. The other option there of course is to let the current set you and just monitor your position closely.

It sounds to me like you're doing it about right, and to chime in on what others have said - If you can pull out your anchor by reversing you need to know it and plan accordingly.

[noelex 77]

Your setting procedure is fine.

Unfortunately, the likely failure is due to inadequate anchoring gear.

Your ground tackle should be able to easily resist full cruising revs for a sustained period of time. If it fails this test, especially reguarly in reasonable substrates, you need better anchoring gear.

If you give the anchor some time to settle or soak, it will often do better, but even full cruising revs in reverse is only equivelent to 25-30 knots of wind, so if the anchor cannot resist this immediately upon dropping, unless the substrate is very soft, it is indicative of poor performance that is unlikely to be secure in any sort of substantial wind.

If you wish to anchor securely it is time to bite the bullet and upgrade the system, even if this means replacing the bow roller etc.

[Cpt Mark]

55lb anchor may be the factory default but IMHO, that is ridiculous. My 35' cat was specced with a 35 lb bruce. It now has a 55lb Rocna. That anchor and it's ability to set fast and hard is THE safety factor in anchoring. On your boat, 55lb lunch hook, np problem. Anchoring in a blow? Nope.

They put on the smallest, cheapest anchor they felt they could get away with. Saving money. On a calm day, no problem.

[BillKny]

This thread has re-enforced for me a very valuable lesson I had learned by experience: NEVER anchor downwind of a production cat unless you know for sure that their ground tackle is adequate.

Jeez... 55lb anchor factory standard for a 45 foot catamaran! That is downright criminal. Or stupid. Or both.

[meirriba]

No brainer...
I go back slowly raising RPM up to maximum possible.
If it holds, it will also hold in a gale...

[Kiwi Dave]

Hi
I also believe that the anchor is too small

[Emmalina]

I found Deltas can be replaced with Rocna's pretty easily . The Charter world (probably the biggest cat customer) Are not big on changing anything from standard. Having been hit by many dragging I wonder what the logic is. I fix a lot of charter stuff and the amount of times they melt the windless by pulling the boat to the anchor is a lot. They all need better ground tackle IMHO.