Dealing with Kelp on prop/rudder/keel

[Letterkenny]

While I love San Diego, the kelp beds are certainly terribly annoying. I was out sailing yesterday on the old boat and due to the strong winds and some larger swell, a lot of the kelp beds from Point Loma have broken free and created thick kelp minefields all throughout the harbor with the rising tide. Inevitably, we ended up hitting a big one that we couldn’t avoid and had it wrapped around the keel, rudder and prop. Since we are currently on a Sailtime boat, we only have so much onboard and that we bring with us to deal with the situation. For our incoming boat, I would like to be fully prepared to deal with the situation.

I keep a knife on me so my wife and I ended up using the boat hook to pull up strands to us and then cut them off. We did this for a while to get the big stuff off the prop/rudder area with the hope being that I could throw her into reverse to get the other stuff of the keel, or, at least, be able to remove some of it this way. When throwing her into reverse several times over 5-10 minutes, the RPM wouldn’t rise at all. I wouldn’t keep it in gear for long without it rising as I was worried about bending the shaft/prop and had no idea why the engine wouldn’t rev up. Eventually, it started to gain RPMs again and was able to cut off the kelp by doing some back downs. If anyone has any thoughts on why the RPMs weren’t moving and the engine wasn’t sounding like it was coming up despite giving it throttle which would normally have it in the 2,000+ RPM range, that would be great.

Our main plan for the new boat is to keep duck tape onboard so we can tape a knife to the boat hook to cut any of it off. I’m addition, I’ll keep a wetsuit, mask, fins and hood on board if the situation is real bad and I need to get into the water. Any other good suggestions?

TL/DR: what’s the best way to get rid of kelp from your prop, rudder, and keel? What caution should be done when putting the boat in reverse to get rid of the kelp?

[chrisr]

the few times it happened while we were racing we had to stop the boat, go head to wind and hold the mainsail backwinded, so the boat sailed backwards.

this cleared the kelp

of course we were doing this as racing and could not use the engine, but it would work just as well if you were worried that using the engine would suck kelp into the prop

cheers,

[JPA Cate]

Outfit your own boat with a folding prop, then you can put the engine in neutral and try to glide through the kelp. With a fixed 3-blade, you probably wound so much up that it was about to stall the engine. For that, best deal is to dive overboard with your knife, and cut it off the prop. Be sensible about how you do it, because you don't want to wrap your legs. On your own boat, I'd suggest a retaining strap for the knife, so you don't drop it. If you have a sharp dive knife, you can take it on your charter rides. But the main thing is to go around the kelp, or have the transmission in neutral and the prop not spinning, if you HAVE to go through.

Also, borrowing from Chris, above, if you sail into it, his suggestion of coming up into the wind, then backwinding the main will push you back, and the kelp may drop off. (It won't get all wound up, from the prop.)

We have had some luck with reversing to get kelp off the keel, but sometime, there will come a time when you're just going to have to get into the water, and cut it away. You might also consider buying a dive light, 'cause it can happen after dark, too.

Knife to boat hook: lash it on tight and then pour boiling water on the lashing to further tighten it. Or, could try screw type hose clamps. Make sure it's soundly on there before using it to cut the kelp.

You could also pull up the kelp and bag it, for disposal at the marina upon your return--why leave it out there for others to foul their boat in?

Ann

[Letterkenny]

Originally Posted by JPA Cate

Outfit your own boat with a folding prop, then you can put the engine in neutral and try to glide through the kelp. With a fixed 3-blade, you probably wound so much up that it was about to stall the engine. For that, best deal is to dive overboard with your knife, and cut it off the prop. Be sensible about how you do it, because you don't want to wrap your legs. On your own boat, I'd suggest a retaining strap for the knife, so you don't drop it. If you have a sharp dive knife, you can take it on your charter rides. But the main thing is to go around the kelp, or have the transmission in neutral and the prop not spinning, if you HAVE to go through.

Also, borrowing from Chris, above, if you sail into it, his suggestion of coming up into the wind, then backwinding the main will push you back, and the kelp may drop off. (It won't get all wound up, from the prop.)

We have had some luck with reversing to get kelp off the keel, but sometime, there will come a time when you're just going to have to get into the water, and cut it away. You might also consider buying a dive light, 'cause it can happen after dark, too.

Knife to boat hook: lash it on tight and then pour boiling water on the lashing to further tighten it. Or, could try screw type hose clamps. Make sure it's soundly on there before using it to cut the kelp.

You could also pull up the kelp and bag it, for disposal at the marina upon your return--why leave it out there for others to foul their boat in?

Ann

We know of the kelp beds but the big swell had it all through the harbor entrance. We were avoiding it as much as we could but there came a point where there were no more openings. We were actually under sail so anything on the prop would have just been picked up versus wrapped around it. I’m a dive master (but really only dive in tropical waters) so I’ll likely just keep some free diving gear and a wetsuit on board if things get real bad.

[JPA Cate]

Do you understand what chrisr was talking, about coming up head to wind, drop the headsail, then winging the main out to backwind it? It is one way to not risk the prop and shaft by using the engine. The wind will push the boat backwards. We've done it when anchoring under sail, to set the anchor.

Good you're comfortable diving. The knife in the hand can be really useful.

Ann

[Scorpius]

We had an interesting experience a couple of years ago in Gwai Hamas (Queen Charlotte Islands, British Columbia). We were leaving a VERY isolated anchorage in the middle of the national park when we picked up a length of 1/2" polyprop which wrapped the wheel and stalled the engine. There was also a strong current running. I was able to get the anchor back down and holding. However, in the process of drifting before the anchor caught, we picked up A TON (literally I think) of kelp which joined the rope on the propellor, rudder, etc. What a mess! I duct-taped my dive knife to the boat hook and tried to clear it - but no luck. I carry mask, snorkel, and fins aboard - but no wet suit (my old one no longer fits! ): - so after establishing an emergency plan with my partner to either get me back on board (if I couldn't make it up the ladder on my own) or who was closest to call for assistance (no Sea Tow around here!) I went over the side in my bathing suit and T-shirt.

It was cold! On one side, the way the current was running, I couldn't get near the prop because of the huge "leaves" streaming in the current. However, on the other side I was able to get at the "stems" and cut them away. There were probably over 50 heavy, mature stems to deal with. However they cut easily and soon the kelp was drifting off in the current. The rope however took nearly an hour of short trips down to get it cut off. It was firmly wrapped many times around the shaft!

Quite the experince. Hopefully it'll never happen again. I was surprised after so long in the cold water that I was still able to get up the ladder without difficulty. Boy that hot chocolate tasted good!

[Phyrcooler]

I feel your pain! Plus we have dual rudders in addition to keel and saildrive. We yank it off with a boat hook, and/or back down occasionally. But we will be adding other solutions. One is a “hook knife”. Basically it’s a long v-shaped blade on a pole. https://sailorssolutions.com/ProductImages/CH01_2.jpg

Next haul out, we’re adding a folding prop. Additionally there is someone locally in SD who has fabricated small fin/blades out of fiberglass or carbon fiber. These are mounted just forward of the rudder to keep kelp out of the space between rudder and keel.

It’s the price we pay for year-‘round sailing and beautiful weather!

[bailsout]

The Herreshoff 28 hull and two blade prop has never caught any kelp, but the harbor is full of eel grass-an unfortunate malady of the recent “save the eel grass” campaign in the harbor. Now there is an abundance of same in the marina and the now flourishing grass appears to be trapping silt and filling in the marina basin.

[guyrj33]

Originally Posted by bailsout

The Herreshoff 28 hull and two blade prop has never caught any kelp, but the harbor is full of eel grass-an unfortunate malady of the recent “save the eel grass” campaign in the harbor. Now there is an abundance of same in the marina and the now flourishing grass appears to be trapping silt and filling in the marina basin.

Those who promoted planting the eel grass knew that it would silt in.

[svRaison d Etre]

Originally Posted by bailsout

The Herreshoff 28 hull and two blade prop has never caught any kelp, but the harbor is full of eel grass-an unfortunate malady of the recent “save the eel grass” campaign in the harbor. Now there is an abundance of same in the marina and the now flourishing grass appears to be trapping silt and filling in the marina basin.

Is the Herreshoff 28 a full keel boat?

We motored through kelp with a full keel and a three blades prop and never caught anything.

[Montanan]

Originally Posted by bailsout

The Herreshoff 28 hull and two blade prop has never caught any kelp, but the harbor is full of eel grass-an unfortunate malady of the recent “save the eel grass” campaign in the harbor. Now there is an abundance of same in the marina and the now flourishing grass appears to be trapping silt and filling in the marina basin.

FYI: The loss of eelgrass in Morro Bay has been vast, dramatically changing the ecology of the estuary.

Morro Bay eelgrass loss may be causing widespread erosion

July 28, 2020

"The large-scale loss of eelgrass in a major California estuary — Morro Bay — may be causing widespread erosion, according to new California Sea Grant-funded research by scientists at California Polytechnic University.

In recent years, Morro Bay’s iconic eelgrass beds, which provide the estuary’s primary living habitat, experienced a massive die-off, declining more than 90 percent since 2007. Efforts to restore the eelgrass have had mixed success in many parts of the bay, and this seagrass is now only found close to the mouth of the bay and sporadically in other regions.

By slowing down currents and decreasing wave forces, seagrasses help stabilize sediment and prevent erosion. Over the last century, Morro Bay has been building up sediment quickly and is dredged annually.

After the eelgrass died off, however, erosion took place in more than 90% of the places where eelgrass previously grew. In some places, the erosion removed enough sediment to cause the water depth to increase by as much as 50% compared to when eelgrass was present. At the mouth of the estuary where eelgrass remains, sediment is still building up as it did in the past.

“These erosional changes are sizeable considering that Morro Bay, a modified estuary, has historically suffered from accelerated sedimentation,” Walter said.

https://caseagrant.ucsd.edu/news/mor...spread-erosion

Just west of San Luis Obispo, Morro Bay is one of 28 estuaries that the U.S. Environmental Protection Agency has designated as critical to the economic and environmental health of the nation. Once dominated by eelgrass (Zostera marina), Morro Bay has been the site of an astonishing collapse: since 2007, eelgrass has declined by 95 percent, from covering 344 acres to less than 15 acres.

[thunderhoof]

I believe the kelp in San Diego is part of God's grand plan to keep SD sailors from feeling too smug. Since it is no longer commercially farmed off Point Loma the kelp growth is a constant pain.

The best defense is to avoid the kelp beds to the West and South of Point Loma. In general kelp grows where the sun can reach the ocean floor. In this area that means a depth of about 100ft. Also, even with just two on board a kelp watch, preferably standing at the mast, is very useful.

Of the many anti-kelp tools that are made, mine is a 30 ft length of 1/2 inch polyester double braid with the middle 20 ft de-cored and filled with lead shot. There is a snap shackle on one end which I snap to one lower shroud base, pass the line outside the lifelines and walk the line around the bow. Then, holding the free end drop the line into the water so it is fairly tight to the hull. Move the line up and down so it cleans the leading edge of the keel. With luck you can drop the line and pull it up before the prop, and then the rudder to floss each of them.

[Captain Scott]

I drove a whale watching boat (49' sailing catamaran with two 30hp universal diesels) out of Santa Barbara for 5 years. Lots of giant kelp.

If you motor through the kelp beds go parallel to the current (in line with the way the kelp is streaming). When I did hit one of those floating patches (which I stayed on the lookout for) I would put the boat in neutral and once stopped, back down firmly in reverse. Never had to go into the water over 500 trips (though I did have a big bread knife just in case). -S

[sv_pelagia]

Scorpius: can you remember WHERE in Gwaii Haanas your kelp/rope experience happened?

Interested as a 3-time HG/GH visitor planning a 4th visit.

(Our best kelp experience was pulling up anchor in Heater Harbour, Gwaii Haanas, which was so full of kelp - - perhaps a metre-high pile on Rocna - - that windlass stalled as it reached surface. Knife taped on end of pole cut through it like butter.)

[Letterkenny]

Originally Posted by thunderhoof

I believe the kelp in San Diego is part of God's grand plan to keep SD sailors from feeling too smug. Since it is no longer commercially farmed off Point Loma the kelp growth is a constant pain.

The best defense is to avoid the kelp beds to the West and South of Point Loma. In general kelp grows where the sun can reach the ocean floor. In this area that means a depth of about 100ft. Also, even with just two on board a kelp watch, preferably standing at the mast, is very useful.

Of the many anti-kelp tools that are made, mine is a 30 ft length of 1/2 inch polyester double braid with the middle 20 ft de-cored and filled with lead shot. There is a snap shackle on one end which I snap to one lower shroud base, pass the line outside the lifelines and walk the line around the bow. Then, holding the free end drop the line into the water so it is fairly tight to the hull. Move the line up and down so it cleans the leading edge of the keel. With luck you can drop the line and pull it up before the prop, and then the rudder to floss each of them.

I stay very clear of that area and usually start my turn north once I hit the 100-150’ contour. The problem on Friday was that there was a good swell we had so starting from the sub base, there was kelp that broke free from the beds everywhere. I was with a couple other boats that experienced similar issues. We had stead 14 knots of breeze and was going 3-4 knots because it getting caught on the keel (this was before hitting a big patch).