Bag full of rocks as a dinghy anchor? What weight will be enough?

...swinging around the anchor in your Hallberg Rassey you'll look back on these days with your Osprey as the most fun you ever had, including the pondering...

That's why I do it. :encouragement: If I never make it to HR territory, my dinghy will still have acquired most of the big-boat features. :rolleyes:
 
Are you planning to sling your hook from the shore, or whilst afloat? If the latter, Mr Newton will come into the equation.

Both...when I come in to land, I'll drop the grapnel so the boat doesn't bump when I go ashore for the trolley. When I'm launching, I'll lob the grapnel out then pull the free end of the warp, to pull the boat off the beach while I park the trolley.

God, it sounds so easy in prospect...can't wait for the reality...:eek:

But which aspect of Newtonian physics were you thinking of?
 
But which aspect of Newtonian physics were you thinking of?

Conservation of momentum, probably, AKA recoil. But don't worry, there's a mass term in that, so throwing a couple of kilos of anchor one way won't move a couple of hundred kilos of boat more than a few inches the other way.

Pete
 
Thanks Mr Believer...et al...

...I must repeat that the grapnel is not intended to replace my Danforth...just to hold the boat temporarily in this launching & landing situation.

If you've already got a Danforth aboard, what's all this heart-searching about? Just launch, jump in, paddle out, drop your b****y anchor, pay out enough rope so that you can get ashore, and go and put your trolley away tidily. What's the big deal?
 
;)

A Mud Weight is a very good way of temporarily securing a vessel to the river /sea floor, it can also be used to advantage in manoeuvring a vessel when berthing or going under low bridges etc. :)

As far as I understand it, it does not count as anchoring to the Harbour bed, so troubles there then.
 
Norman, it's mainly a matter of scope. I was thinking that a stone-bag or grapnel will grip on a very short line, such as I can toss out from the knee-deep breakers.

Going aboard, temporarily abandoning the trolley and paddling around in the boat for a few minutes just in order to drop an anchor which will only be needed for 90 seconds, doesn't seem to justify the length of warp (and of time and bother required) for successfully setting the Danforth.

As with most questions I ask here, the circumstances involved don't quite match what many people are used to. I reckon a grapnel will substitute for a human holding the boat.
 
I'm wondering if you could fill those bags with styrene foam and use them as an emergency floatation devices instead of life jackets (it would be a lot cheaper). I priced life-jackets the other day and they want an arm and a leg.
 
I'm hopeful that I won't ever need emergency flotation devices on the dinghy...some loony has stuffed all the hull-cavities with hundreds of air-tight empty lemonade bottles, so short of being run down and crushed, I don't think she'll sink. :rolleyes:
 
I can sell you a rock for 50 quid to go in the bag if that's any help :p

I should add that it's a special Marine rock, thereby justifying the pricetag.

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I'll take two...as long as they have the nice copper-plate Nauticalia name on them. Bargain.

Thank you for your order, dancrane! I am sure you will be delighted with your purchase. I have debited your credit card for the full amount of £184.70 (inc P & P). Once the Marine rocks arrive from our supplier we will despatch them within 28 days.
 
I suppose tests have been done to make sure that these rocks will not squash any seahorses when you chuck them overboard. Worse still rip up half an acre of eel grass when you pull it back. You know that the greens do not like you wealthy yottie types spoiling the wildlife

I would not want your osprey to be declared a marine conservation zone
 
Our special Marine rocks come from a sustainable source and are seahorse friendly.

...and are styled to resemble Chris Packham's head.

Also available this Christmas season...Yottie's Gin, for swilling, as you dredge the seabed with your ground tackle.
 
Some thoughts on an interesting thread:
There is a launching place in NZ i am told where the fishing is good but there is no room for boat trailers so the locals have attached flotation and anchors to the trailers. The trailers just float awash as it were so it is easy to slide the boat over the trailer while both are floating. Procedure is that they disconnect trailer from tow vehicle - hold it on the trailer brake just out of the water while they park the vehicle, then launch boat with trailer still attached. Motor out a short distance and anchor the trailer which floats semi submerged until they return at the end of the days fishing and reverse the process.

In your case you could head the boat out a few metres, anchor and let her drift back close to shore, slide the floating trolley out from under and go and dispose of it.

The other options is the use of a drone to take the anchor out. Commercially available drones are now available to amateur fishermen to take fishing lines out and they go a long way with what ends up being a lot of weight(several kilograms).


one other thought. Why not a permanent anchor offshore with a chain laid on the bottom and fixed near the slip. Its hardly going to impede people when not in use.

cheers
 
Interesting additions, thanks John.

I'd gladly sink a big concrete block out beyond the slipway, with 60ft of chain leading up to a pin near the high-water mark...it needn't be costly or unsightly in my view, but the idea met with frowns from my club's members rather than positivity. I'll suggest it again.

The idea of trailers left afloat is interesting...but surely they were trolleys, intended to be immersed, rather than road trailers? I thought the latter was wholly unsuited to dunking, because the bearings suffer.

I strapped empty lemonade bottles (repressurized by an hour in the deep freeze, lids off) onto my launching trolley, mainly to help spread the burden of the hull over a greater area than the axle-bar. It worked well, until the trolley went in the water, when its buoyancy made it very difficult to separate from the boat, or to slide under the boat for hauling out.

And, once again, I wouldn't expect members of my club (a nice crowd on the whole) to be very delighted if their route down the slipway involved negotiating my floating trolley.

Thanks anyway.

I'll buy the grapnel, see how far I can throw or swing it, and review my plan then. :encouragement:
 
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For the loads and times involved, no need for concrete and chain. Any random old anchor or weight (sack of rocks?) and a length of beach find rope would do. Keep it flush with the ground and it can't get in anybody's way.
Isn't there another singlehander at the club who you could persuade to back this idea? Are you the only person who is inconvenienced?
 
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