Scottinva
Well-known member
If you fish those areas of the James you are very close to Jim Starkey at JRJ. He may have been the one that built the boat, but if not, he could certainly help you with your issues.
Scott
Scott
TinBoats.net
The original aluminum boat site!
4 stroke 60/40 on 1648 River Rhino with UHMW??
- Thread starter rotus623
- Start date
Help Support TinBoats.net:
rotus623
Well-known member
Scottinva said:
Yea he built the boat and I don't live far from him at all.
rotus623
Well-known member
Ok fellas,
So I brought the boat out to Jim at JRJ. He took a look at it and said everything looked good as far as motor height, etc. BUT he trimmed the engine up and looked at the impeller and told me that the wrong side of the blades had been filed. Apparently the person that owned the boat ahead of me had filed down the wrong side. So when I saw the dull edge, I continued to file it down to sharpen the leading edge. He told me that the bottom edge of the blades shouldn't be tampered with and what my boat was actually doing was pushing water down rather than up into the jet housing. Dang man, expensive boo-boo!! Here is the impeller:
So I brought the boat out to Jim at JRJ. He took a look at it and said everything looked good as far as motor height, etc. BUT he trimmed the engine up and looked at the impeller and told me that the wrong side of the blades had been filed. Apparently the person that owned the boat ahead of me had filed down the wrong side. So when I saw the dull edge, I continued to file it down to sharpen the leading edge. He told me that the bottom edge of the blades shouldn't be tampered with and what my boat was actually doing was pushing water down rather than up into the jet housing. Dang man, expensive boo-boo!! Here is the impeller:
rotus623
Well-known member
P.S. if anyone has an aluminum or ss impeller they want to sell let me know!!
LarryMc
Well-known member
Actually, OBJ says that the upper side should not be filed down, just to file the burrs off enough to smooth out the upper side. As best I can tell from your photos, your impeller looks just like the illustrations in their Sharpening Instructions.
Check it out;
https://outboardjets.com/download/miscellaneous_instructions/RESHARPENING%20IMPELLER%20BLADE%20LEADING%20EDGES.pdf
Check it out;
https://outboardjets.com/download/miscellaneous_instructions/RESHARPENING%20IMPELLER%20BLADE%20LEADING%20EDGES.pdf
rotus623
Well-known member
Yea man that's what I thought!! Well what is ol Jim talking about then? Man I sure would hat to buy an impeller and not have it fix my issue. You don't happen to have an old aluminum impeller
Laying around do ya?
Laying around do ya?
rotus623
Well-known member
Oh and they talk about bending he blades upward on OBJ but that's some pretty thick metal. How in the world???
LarryMc
Well-known member
rotus623 said:Yea man that's what I thought!! Well what is ol Jim talking about then? Man I sure would hat to buy an impeller and not have it fix my issue. You don't happen to have an old aluminum impeller
Laying around do ya?
Actually, I do. It's a 6 7/8" (part# 106.23) that I bought from OBJ several years ago. It's in good shape if you decide you want to buy another aluminum impeller. The leading edges have a few dings in them but otherwise it's not worn at all. Last time I had in my motor, all the shims were still on the bottom and there was .030" clearance.
I didn't see anything about bending the blades up. Got a link?
rotus623
Well-known member
Oh sorry it says blend underside of the blade duh....
Yea man shoot me a pm with what you will take for the impeller. I'd like to at least try it and see if it helps with my cavititation. I think there has been too much taken off my impeller.
Yea man shoot me a pm with what you will take for the impeller. I'd like to at least try it and see if it helps with my cavititation. I think there has been too much taken off my impeller.
Lil' Blue Rude
Well-known member
You might be able to save your impeller, or at least make it little better. Attached a pic, trim it down like the red line shows and I think that should help it out. I've had impellers sharpened like that that cavitated on holeshot and I trimmed them like the pic and they hooked up better.
I' not even getting started on the top vs bottom thing. :roll: :mrgreen:
I' not even getting started on the top vs bottom thing. :roll: :mrgreen:
Attachments
rotus623
Well-known member
Lil' Blue Rude said:
Lil blue thanks for your feedback. I have read some of your past posts regarding taking too much off the bottom of the blade, yielding EXACTLY what my symptoms are. I think you are on to something. I will try and salvage this impeller the way you describe, but am afraid that I will create an imbalance of the impeller. Guess you would feel it if it is off.
I'd like to see a pic of your impeller after you dress it.
Thankfully Larry has saved my @$$ and let me get a used impeller he doesn't need anymore. Don't have hundreds of dollars to be investing here!!
handyandy
Well-known member
Idk why obj suggest to sharpen the way they do. It works yes, but sharpening the way rude does gets much performance. I sharpen the top of mine works better for me.
rotus623
Well-known member
Ok fellas, thanks for all the support and ideas!! I think you guys and ol Starkey hit the nail on the head. I went out yesterday with a good friend of mine and the boat on plane with very little slippage/cavitation in a lite chop. On glass it didn't slip at all!! It's like a whole different boat.
Now the wind picked up and if the wind and current were going in a certain direction the cavitation would worsen, but I guess thats all in the game. I have the fins from outboard jets that I am going to put on for some less than stellar conditions.
If I had my passenger come up to where I set, the boat hopped up on plane in one boat length and ran shallower. It was awesome. I am going to try and figure out a way to get the passenger up closer to me when running. I am also considering moving the battery up front.
Now the wind picked up and if the wind and current were going in a certain direction the cavitation would worsen, but I guess thats all in the game. I have the fins from outboard jets that I am going to put on for some less than stellar conditions.
If I had my passenger come up to where I set, the boat hopped up on plane in one boat length and ran shallower. It was awesome. I am going to try and figure out a way to get the passenger up closer to me when running. I am also considering moving the battery up front.
rotus623
Well-known member
I was afraid that bringing weight forward would take the rear of the boat up too much and make cavitation worse, when in reality, bringing the stern up basically elimintaes the cavitation even further. You guys think float pods are a good next step?
Which impeller did you use for this last run? I've never really noticed much cavitation except when trying to make a quick 180 turn at speed or going over multiple boat wakes, but I'm on a river where there really isn't too much activity. I never give it full throttle to get on plane, usually 1/2 or 2/3 at the most so I don't notice cavitation in that situation and that's with my chewed up impeller. When I had 3 people up front, I did notice the cavitation and had one guy move back to the middle with me, but I'm usually out by myself so that isn't a concern.
rotus623
Well-known member
I used a good used impeller that I got from Larry "The Man" MC!! It had never been filed at all and I just stuck it on there as is.
Clearly, the cavitation issue was caused due to way too much filing of the under side of the impeller. I kept all other factors exactly the same, down to the amount of gas I had and the person that I brought with me. I am very happy so for. Can't wait to add the fins on to see how they do in windy/choppy waters.
Clearly, the cavitation issue was caused due to way too much filing of the under side of the impeller. I kept all other factors exactly the same, down to the amount of gas I had and the person that I brought with me. I am very happy so for. Can't wait to add the fins on to see how they do in windy/choppy waters.
handyandy
Well-known member
I don't see why pods would hurt they would just give you more flotation in the back of the boat to help make it draft less.
rotus623
Well-known member
Ok fellas,
I am bringing this thread back to life here.
I am playing with ideas to get the boat to draft less while on plane. I also still have some undesireable cavitation in certain condition. It is not terrible, but I would like to make it better. I would also like to help with holeshot some. I really do appreciate having the 4 stroke engine though. It is so quiet and smooth. I can toss my anchor over and pop her in reverse and just wait til the anchor locks in. Then I leave it in reverse and throw out the back anchor. Snug up the lines and cut the motor off. Works like a charm!!
That being said, I did notice that the bottom of my boat, just before the tunnel, has about a 1/4" deep hook. The hook is 2' long and looks like I need to hammer it out from inside the boat. My guess is because of the weight setting on the roller trailer. In order to do that I need to pull the floor, and possible cut the rear box out (which I dont like anyways.)
Do you think the hook could be adding to the cavitation?
I am hoping to bring the passenger up front with me to help with weight distribution. When I am the only one on this boat it rides LIKE A DREAM!! Add another @$$, and not so much. My fear is that if I bring the tail end up more, I will cavitate more in the chop. Ulgghhhh.
I am bringing this thread back to life here.
I am playing with ideas to get the boat to draft less while on plane. I also still have some undesireable cavitation in certain condition. It is not terrible, but I would like to make it better. I would also like to help with holeshot some. I really do appreciate having the 4 stroke engine though. It is so quiet and smooth. I can toss my anchor over and pop her in reverse and just wait til the anchor locks in. Then I leave it in reverse and throw out the back anchor. Snug up the lines and cut the motor off. Works like a charm!!
That being said, I did notice that the bottom of my boat, just before the tunnel, has about a 1/4" deep hook. The hook is 2' long and looks like I need to hammer it out from inside the boat. My guess is because of the weight setting on the roller trailer. In order to do that I need to pull the floor, and possible cut the rear box out (which I dont like anyways.)
Do you think the hook could be adding to the cavitation?
I am hoping to bring the passenger up front with me to help with weight distribution. When I am the only one on this boat it rides LIKE A DREAM!! Add another @$$, and not so much. My fear is that if I bring the tail end up more, I will cavitate more in the chop. Ulgghhhh.
jtf
Well-known member
I'm on the back end of this topic, it's interesting because I run a UHMW Hyde drift boat now, and three former UHMW bottom boats, one we retrofitted the bottom in the machine shop.
All the boats are flat/rocker bottom without strakes. And that probably makes a big difference. I don't think the weight is as big a factor, the material we use can't be much more than 30lbs on a 14ft. The Koffler RMTB 14/54 would get up and go with 10hp and three adults. Doubt it ran 20mph, but it responded well, did slide pushed hard in a turn but that's how the hull is supposed to do on these and why we can run class III.
Jon boat hulls are different. If I try it on one, will put the UHMW between the strakes and expect to loose some handling. I think my UHMW bottom adds some lift while drifting.
All the boats are flat/rocker bottom without strakes. And that probably makes a big difference. I don't think the weight is as big a factor, the material we use can't be much more than 30lbs on a 14ft. The Koffler RMTB 14/54 would get up and go with 10hp and three adults. Doubt it ran 20mph, but it responded well, did slide pushed hard in a turn but that's how the hull is supposed to do on these and why we can run class III.
Jon boat hulls are different. If I try it on one, will put the UHMW between the strakes and expect to loose some handling. I think my UHMW bottom adds some lift while drifting.
Hey rotus623, I guess you are the one on Cville Craigslist that was selling the 60/40... I live in western Goochland and just acquired a 1997 sea ark allwelded 17' with a 90/65 2 stroke... Would be glad to demo for you though my boat is lighter it would be a decent comparison. I had mine out for the first time since buying (waiting on the title) two weeks ago and it does 32 down river and 30 up... at Watkins landing...
