Dealing with Kelp on prop/rudder/keel

[Don C L]

One thing I do appreciate about my old hull around here is that I don't worry, or have to stop, if I go over kelp or lobster pot buoys. But when I sailed other boats, yes reverse was your friend, and if not, live with it till yer back in the harbor or get the wetsuit on... or just jump in with the knife in yer teeth. Make sure to get some shots of that to show the grandkids. One other thing though, to make sure us long-keelers don't get too smug, the kelp forests on the Cal coast sometimes hide big, shallow rock outcrops, so I'd suggest not venturing too far into a kelp bed unless you have really good visibility, going slow and someone is on the bow keeping an eye out.

[waterman46]

Originally Posted by Montanan

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.

Incredible number of conflicting thoughts in that quote whether you are an environmentalist or a boater. First they mourn the loss of eelgrass, saying there is now "widespread erosion" (bad for environmentalists) but that this has caused an increase in the depth (good for boaters). Then it's written that historically Morro bay has "suffered" from accelerated sedimentation due to a large amount of eelgrass. Wait a minute, I thought they wanted the eelgrass, but they say with the eel grass they "suffer".

Sometimes you just can't win.

[bailsout]

This is humans messing around with nature: fixing it, breaking it and then trying to fix it again. Most of this fixing began with the construction of the spit and breakwaters and the state park marina. And so the humans will begin to squabble over what is best or more natural and “man”ipulate it again and again.
Sorry, it was not my intention to subvert the OP.
BTW, my Herreshoff is a full keel, transom hung rudder and tiller.

[Nord Sal]

Use hose clamps to attach a knife to a boat hook rather than adhesive tape. This will hold the knife tighter and it'll cut better if it doesn't wiggle. You also won't have adhesive residue on your knife when you're done.

I had to cut out an 1-1/2" poly line that had fouled my prop a few years ago this way, and kelp quite a few times too. A divers mask is helpful to see better.

[Oohla]

Look at Hook Knife 2 from Sailor Solutions
https://sailorssolutions.com/?page=P...ails&Item=CH03

[Letterkenny]

Originally Posted by Oohla

Look at Hook Knife 2 from Sailor Solutions
https://sailorssolutions.com/?page=P...ails&Item=CH03

Definitely buying this for the boat.

[Pauls]

I ran a commercial boat out of Santa Barbara, it was a common experience to need to work thru a huge kelp bed by the offshore islands. The boat would pick up a load of kelp. After clearing the bed we would just back down for a few seconds. The kelp would all come off as the boat reversed. We never dove. This was common practice.

[Letterkenny]

How much can your prop take backing it down? I don’t want to risk bending or breaking the prop or shaft.

[Phyrcooler]

Originally Posted by Letterkenny

How much can your prop take backing it down? I don’t want to risk bending or breaking the prop or shaft.

Not sure your question. Backing down... is simply reversing to get the floatsam off the leading edge of your keel, rudder and saildrive (if you have one). I’ve never had a problem with the prop chopping up the kelp - but if somehow you felt it was restricting prop movement, I would stop and manually clear the prop.

[Pauls]

Your prop and shaft are designed to take the full power of your engine. The direction of rotation - ie forward or reverse - makes no difference. It is safe to reverse at full power.

[Letterkenny]

I guess what I mean is does the kelp have the potential to hurt the prop/shaft?

[Don C L]

Originally Posted by Letterkenny

I guess what I mean is does the kelp have the potential to hurt the prop/shaft?

Kelp is tough, but not that tough.

[sailingabe41ds]

Originally Posted by 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

I am in Channel Isl Harbor just south of you and frequent the Channel Islands for the last 20 years. I too have done exactly that and never have had a problem. Best thing is to know your area and avoid the kelp.
Abe

[Letterkenny]

Agreed it’s best to avoid but that day was quite bad since it all broke off from the point and into the harbor entrance so no way of avoiding. I’d still rather run into this here than the times I have had it wash through the surf while surfing. That’s a very dangerous spot to be in.

[RHarbert]

Originally Posted by 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?

Look into Spurs...https://youtu.be/Fsd1qkWa8ps