After a broken prop and a tangled prop, I decided I need a prop guard. But what kind?

[chuser]

After breaking a blade off of one propeller and wrapping a dirty old shirt around the new one, I've come to the conclusion that I need a prop guard of some kind. I keep going in unknown waters where I get the idea that local boaters aren't supposed to go into. I thought my jonboat's super shallow draft would help, and it does, but the prop keeps hitting underwater obstructions.

I have a 15hp Hangkai engine with a 10.5 inch prop. This means I'd need an 11 inch prop guard? It seems like maybe that would be a bit tight - I don't know though. What size prop guard is suitable?

From all of my research, it seems there are three functions of a prop guard: 1) to protect swimmers, 2) to protect the prop from getting tangled, and 3) to protect the prop from striking rocks. I found a red plastic prop guard, but not sure which of the three kinds it is. Anyone have any insight?

 

[achris]

Prop guards designed to protect humans, and other life from being struck by a blade, not to protect the prop from damage (despite what the advertising says). If anything, having a guard will increase the likelihood of damaging the prop should something get in there.

The only way to ensure that the prop isn't damaged is to stay home.

Chris.........

 

[briangcc]

I have to agree with achris here. That's not going to stop the prop from sucking in a plastic bag/shirt/towel/rope/etc and jamming the prop. In fact it may latch onto the guard and do more damage in the process.

I think you may be better off switching to a jet powered boat considering the damage done. You'll still suck in rocks/shirts/debris so be prepared to keep clearing that given the waters you're frequenting. But you won't be replacing a prop.

 

[Scott Danforth]

the skeg is to protect the prop from rocks

the prop guard is to protect people and wild life

props are a consumable

 

[JimS123]

I solved that problem years ago. When I go into unknown waters I raise the engine and drop the oars.

Some people swear by Caviness and I've had them before, but I like Beavers best.

 

[Bob_VT]

. I keep going in unknown waters where I get the idea that local boaters aren't supposed to go into.

Jon boat? two choices - use your oars stay out of where "local boaters aren't supposed to go"

or even a small water jet type trolling motor

 

[Sea Rider]

Stay away from Prop Guards, are useless for normal boating, will break if hits something like a sandbank, rocks, submerged hidden things, etc. Are only good for rescue boats, surf shuttle boats, shore patrol boats dealing with bathers, swimmers.



If your motor was correctly propped running middle to max wot rpm range as loaded, will need to install one less prop pitch for motor to rev to same previos rpm range.. Installed 3 Prop Guard brand on 3-30 HP motors, didin't last one week, ended breaking when hitting something at low speed..

Happy Boating

 

[TyeeMan]

Depth finders are always a good idea. Adjust your offset to the bottom of your outboard and you should be fine.

Or a composite prop. . .

 

[Scott Danforth]

as a refresher, the OP is in China, this is a chinese made 7hp air-cooled motor on a 12' john boat

my suggestion, a few extra props on board and some tools to swap it the next time the prop becomes toast

 

[harringtondav]

Sorry about diverging from the OP's subject, but this is kinda related....and not worthy of a new post.

I became familiar with Kort nozzles while watching a web vid on barge tow construction. Kort nozzles are common on these monsters.

Is anyone familiar with these being used on pleasure boats? I'd guess big vee hull houseboats.

 

[chuser]

Actually I upgraded from the old 7hp engine to a secondhand 15hp water-cooled two-stroke Hangkai. Now I can get up on plane! I went from 6 knots to 18 knots top speed. :happy: Thanks for remembering about me though!

It's got a 10.5 inch prop. I was worried about the prop being scuffed up, but that's not an issue because I got a new prop when I broke a blade off the old one. :cold: Stay out of the unknown waters? Well that's where all the fun is! There's no glory in

I agree a jet drive would be best. But it's way out of my budget range. Or one of those gooseneck lower units for super shallow water. Meh, I've got what I've got.

I guess there isn't really anything to protect a prop, eh? I might see if I can get a "skeg guard" fabricated at a machine shop or something. That should protect against underwater rocks, right?

 

[Sea Rider]

A skeg guard would be more suitable to protect prop against sandbanks, rocks, submerged logs, etc, much better than a Prop Guard will do. If like venturing boating on dangerous waters do it at low speed, can trim the motor up for prop to bite very near the water level...

Happy Boating

 

[achris]

... Stay out of the unknown waters? Well that's where all the fun is! ...

Under international maritime law, a master who allows his vessel to run aground, or be damaged by impact with the seabed is faced with charges. It's a real pity the same doesn't apply to recreational boaters. It might put an end to the flagrant disregard for safety at sea and reckless behaviour. (I work on ocean going vessels, and I take safety at sea VERY seriously.)

Stock up on props...

Chris.........

 

[chuser]

Look, the unknown waters aren't some kind of shipwreck rocks. They're just out-of-the-way or shallow or disused. Many of these canals were built centuries ago when agriculture was delivered into the city by punts being poled by boatmen. I have picked my way through a bunch of them and they are super cool. The latest one I found had a cul-de-sac at the end with a fountain and water gardens. The fountain was there to aerate a stagnant area and the flowers were to pull pollution out of the water but it was no less beautiful for being so.

The whole reason I got a flat jonboat in the first place was to get into these places, and to squeeze under the many low bridges where center console and pontoon boats can't go. The waters here are profoundly different from what's back home. I grew up on boats so I know the score. An airboat would be ideal, but they don't have them here. It would be too high to fit under the bridges anyway. A jetski would really be the best, but they're way out of my price range and can only take a single passenger.

It's not even "at sea", it's fresh(-ish) water. I couldn't get out into the ocean if I tried, there are locks that prevent access to the main river that leads to the sea. The bow wakes from the many large vessels in the river would swamp me even if I could get there. So I'm going to stay in the canals where the water is 4-6 feet deep most places and the banks are right there if I ever get into trouble.

 

[harringtondav]

They're just out-of-the-way or shallow or disused. Many of these canals were built centuries ago when agriculture was delivered into the city by punts being poled by boatmen. I have picked my way through a bunch of them and they are super cool.

I understand. The first boat we owned, and still own is a 16' Grumman alum canoe w/a 4 hp merc 'Gnat' on a side mount. We used the heck out of it on a mid sized river close. Plastic prop. I'd lean port in shallow water so the prop could splash us over shallow areas. We lived in NJ for two years, and once took this rig on the Delaware and Raritan canal. We'd tuck low and lean to pass under the causeways.

Now we boat in the Mississippi with a larger boat. I know the our pool and two above us like the back of my hand. But river trash and sunken, water logged 'deadhead' logs can bite at any time. That's why I always carry a spare tire, thrust washer, lock collar, lock tab washer and nut, plus prop wrench.

 

[QBhoy]

If you get such a thing, you may well find you will be close to not planing at all and run even deeper in the water.
A depth sounder won’t be much good either, unless you manage to find one that somehow tells you the depth anything other than what’s underneath you at that precise second. By then it’s too late usually.
would a jack plate help you any ?

 

[chuser]

I thought about a depth finder, but the transducer needs to be attached to the hull. And I abuse the bottom of my hull by scraping it over things. I haul the boat ashore and scratch it up that way. And yeah to be useful it would have to be mounted at the bow instead of the stern, to show me what's coming up rather than what I just ran over. But a bow transducer would get broken off even faster.

A jack plate is a good idea, I'll see if anyone has heard of one. Pleasure boating is a stunted, hardly developed industry. Most waters are off-limits to anyone but licensed fishermen. The supporting infrastructure just isn't there. Something you could just order online at the drop of a hat in America isn't available here. The good news is there are lots of machine shops that can fabricate things, and they're very good at copying, but I haven't found one yet. Gotta work on that.
The more I post on boating forums asking for advice, the more I realize just how out of the ordinary my use case is. :cold: People want to go bass fishing or pull skiiers or are commercial ship captains, while I'm going under cobweb footbridges built hundreds of years ago and running over junk people throw in the canals. They've got some kind of mission in the water, while my mission is just to be in the water. I just run around and explore places where I'm not supposed to be. Not the "illegal" kind of not supposed to be, but just "no reason for anyone to go there" kind.

I got a GoPro clone (SJCAM SJ4000) and am shooting a bunch of video. I'll post some when I edit it together. I see the most unusual things on the water that you have to see to believe.

 

[chuser]

Broke another prop today. It wasn't even in unknown waters. Well, it was, but not the usual kind. It was just between a bridge and an island, and I was going around to see if it was really an island or just a peninsula. Engine starts grinding and pops up, I pull the kill switch but it was too late. Walked home. Again. The marina man will come to tow it to the shop tomorrow for a new prop. Again. :faint2: I begin to see why people call props disposable. :facepalm:

I guess I need a skeg guard. Mac's river runner looks like a good one? Even though my skeg is fine. You can see the run-in with the bottom coated it with mud. It's the props that keep breaking off. According to reviews it takes off your top speed, but I can't break a prop every two weeks, this can't continue. :blue: I just have to see if I can find a distributor that will ship to China.

 

[Bondo]

Ayuh,..... You just need to learn how to stay outa skinny water,......





Or, buy a Canoe, 'n paddle it,.....

 

[achris]

Try slowing down. To break a blade off like that, you must be running quickly.