is motor installed correctly? have porpoising problem at higher rpms

[greenbush future]

Re: is motor installed correctly? have porpoising problem at higher rpms

Let's just settle this ONCE AND FOR ALL! I'll offer a bounty of $5 billion dollars (no not really) for anyone who has ACTUALLY TRIED smart tabs on ANY boat who doesn't believe wholeheartedly that they will make a night and day difference on the O/P's boat and make the porpoising problem instantly disappear.

Further I'll offer a $10 million (again not really paying lol) for ANYONE who ever tried smart tabs and took them off in favor of an add on foil for the lower unit.

Please note the below smiley which according to internet protocol means that this post however pointed is in fun and you aren't allowed to get mad OR sue me for millions of dollars! lol

:laugh:

I bet the tabs will get rid of the problem too, but I also beleive that if a 16-19 foot boat needs trim tabs to plane out and not bounce, there is a problem with the boat, or how it's rigged. And trim tabs arent fixing that problem, they are a band aid. For the most part no boat that small should really need tabs unless there is a special situation. I'd add a bag of sand to the bow before I add tabs to the back in that special situation. I dont think this boat, based on what he offered, is "special", it most likely is rigged wrong, or the hull has a hook. This will be interesting to see what the real problem is.

 

[WIMUSKY]

Re: is motor installed correctly? have porpoising problem at higher rpms

I'd add a bag of sand to the bow before I add tabs to the back in that special situation.

Funny you mention sand bags. I was just thinking about those sand tubes Menards and whoever else sells them. If he has room below the deck, I bet a couple of those would solve the issue. Could start with one. I agree, something is amiss and just needs to be tweaked.....

 

[beardeddone]

Re: is motor installed correctly? have porpoising problem at higher rpms

I bet the tabs will get rid of the problem too, but I also beleive that if a 16-19 foot boat needs trim tabs to plane out and not bounce, there is a problem with the boat, or how it's rigged. And trim tabs arent fixing that problem, they are a band aid. For the most part no boat that small should really need tabs unless there is a special situation. I'd add a bag of sand to the bow before I add tabs to the back in that special situation. I dont think this boat, based on what he offered, is "special", it most likely is rigged wrong, or the hull has a hook. This will be interesting to see what the real problem is.

This certainly will be interesting to see what is the real issue here, the boat I keep mentioning for my porpoising problem is also now an interesting one for me, although I no longer have that boat it probably will continue to be a mystery, but it was factory made no engine changes, one owner, kept under a large car port, never leaked water or showed it had water anywhere in it sitting anywhere, no hull damage and was well cared for when we got it, never had any problems with the motor or any other thing I can think of, it was very responsive and would easily go 45mph with just me in it and about 42mph with two people in the boat, which is about normal for a Nitro Boat with a Mercury 90 Tracker as did the manual say and this was with spedo and gps readings and this with an aluminum prop, so for me what caused this boat to porpoise in the first place when it did as nothing changed during that time period..

Maybe the extra weight is the problem for greenpathy, but for me it wasn't as nothing was changed, I hope he finds out and let's us know..

 

[smokeonthewater]

Re: is motor installed correctly? have porpoising problem at higher rpms

I bet the tabs will get rid of the problem too, but I also beleive that if a 16-19 foot boat needs trim tabs to plane out and not bounce, there is a problem with the boat, or how it's rigged. And trim tabs arent fixing that problem, they are a band aid. For the most part no boat that small should really need tabs unless there is a special situation. I'd add a bag of sand to the bow before I add tabs to the back in that special situation. I dont think this boat, based on what he offered, is "special", it most likely is rigged wrong, or the hull has a hook. This will be interesting to see what the real problem is.

A hook in the hull would not cause it to porpoise... It would do just the opposite and plant the bow firmly.. rocker on the other hand could cause it to porpoise but it is very unlikely to have rocker as that would mean the hull was somehow pushed down in front of the transom instead of up

I agree that there is likely a reason that he is having trouble but he seems a bit resistant to finding it in the manner that I would choose.... The first thing I would do is trash that wedge and mount the engine true and centered with the anti vent plate exactly 1" above the keel when parallel to it... then I would start looking for any weight I could move forward.
I would also have a tach on board along with a gps and look into a better prop (I am a firm believer in having a spare prop and a prop wrench on board anyway)

WIMUSKY
The reason nobody really remembers seeing smart tabs on small craft is that they are a fairly new product... hydrofoils have been around in one form or another for the better part of a century.

 

[greenpathy]

Re: is motor installed correctly? have porpoising problem at higher rpms

A hook in the hull would not cause it to porpoise... It would do just the opposite and plant the bow firmly.. rocker on the other hand could cause it to porpoise but it is very unlikely to have rocker as that would mean the hull was somehow pushed down in front of the transom instead of up

I agree that there is likely a reason that he is having trouble but he seems a bit resistant to finding it in the manner that I would choose.... The first thing I would do is trash that wedge and mount the engine true and centered with the anti vent plate exactly 1" above the keel when parallel to it... then I would start looking for any weight I could move forward.
I would also have a tach on board along with a gps and look into a better prop (I am a firm believer in having a spare prop and a prop wrench on board anyway)

WIMUSKY
The reason nobody really remembers seeing smart tabs on small craft is that they are a fairly new product... hydrofoils have been around in one form or another for the better part of a century.

i'm a bit resitant b/c i want to go fishing tomarrow and the porposing is not a make or break deal...it takes time to unmount that motor and remove that wedge,,,its thru bolted threw the hull.. i have a full time job also..i have a tach already on board,,,i do however need a gps(if its the speed your wondering) the speedometer quit working this summer for some reason.. but i have a tach..

 

[jestor68]

Re: is motor installed correctly? have porpoising problem at higher rpms

i'm a bit resitant b/c i want to go fishing tomarrow and the porposing is not a make or break deal...it takes time to unmount that motor and remove that wedge,,,its thru bolted threw the hull.. i have a full time job also..i have a tach already on board,,,i do however need a gps(if its the speed your wondering) the speedometer quit working this summer for some reason.. but i have a tach..

If you have not yet tried the ballast in the bow idea(a bag of play sand?), you are ignoring the KISS principle.

 

[smokeonthewater]

Re: is motor installed correctly? have porpoising problem at higher rpms

I'm not down on you at all... I was just explaining my suggestion to just run with the tabs and be done with it....
At least give the folks at nauticus a call and talk to them about your issue.... their customer service is second to none.

 

[oldboatlover63]

Re: is motor installed correctly? have porpoising problem at higher rpms

Tuck the engine in as close to the boat as possible, give it a try. Very simple, easy experiment. In the tucked position it will try to shove the nose down. It will either work or it won't. The easiest way to find out is to try it.

 

[greenpathy]

Re: is motor installed correctly? have porpoising problem at higher rpms

I'm not down on you at all... I was just explaining my suggestion to just run with the tabs and be done with it....
At least give the folks at nauticus a call and talk to them about your issue.... their customer service is second to none.

i know you werent downing me...i did notice when i pulled my boat out of the garage and stood way back that the motor is tilted to 1 side a little...and i could see slippage on 1 of the bolts... i ran the boat today on the lake and had my wife sit a little behind the front fishing seat and trimmed the motor all the way down and no porposing issue at all..water was calm and slick..no wind or chop..i will still level up the motor at least and i will try to get a friend to help me uninstall the wedge..if it still happens then its either sandbag time or smart tabs.. or hydro foil.. not sure what..a big than you to all who have responded..i really appreciate all your help..it has made me look at me set up alot better with all your responses.. so again thank you to all who have helped me.

 

[cyclops2]

Re: is motor installed correctly? have porpoising problem at higher rpms

Is the Nissan a good bit heavier ? If yes.

ALWAYS take the wife along.

It does seem as if the Nissan was just heavy enough to require some compensating weight in the front of the boat.

Good luck with it.

 

[greenbush future]

Re: is motor installed correctly? have porpoising problem at higher rpms

A hook in the hull would not cause it to porpoise... It would do just the opposite and plant the bow firmly.. rocker on the other hand could cause it to porpoise but it is very unlikely to have rocker as that would mean the hull was somehow pushed down in front of the transom instead of up

I agree that there is likely a reason that he is having trouble but he seems a bit resistant to finding it in the manner that I would choose.... The first thing I would do is trash that wedge and mount the engine true and centered with the anti vent plate exactly 1" above the keel when parallel to it... then I would start looking for any weight I could move forward.
I would also have a tach on board along with a gps and look into a better prop (I am a firm believer in having a spare prop and a prop wrench on board anyway)

WIMUSKY
The reason nobody really remembers seeing smart tabs on small craft is that they are a fairly new product... hydrofoils have been around in one form or another for the better part of a century.

I would agree with your view on this that a hook wouldn't cause this problem, it might solve a listing situation, but it would have to be pushed out in order to cause a bouncing bow. Sounds like he is making progress on his solution, just needed some weight in the bow to fix it, wife, sandbag, either seems to work.