Classic 16 Sea Trials

[dfunde01]

2005 Classic 16 sea trials today were a major disappointment. That sucker is unstable to the point of being dangerous in any type of chop at all and is really crazy if you trim up at all. We are talking fairly light traffic on Hartwell today.

Results on GPS tests. 4.3 EPI 21 P VENGEANCE SS, trim full down.

3000 rpm = 47.7 on GPS

It appears that I may have a serious tach error.

Below 2800 - 3000 rpm porpoising gets progressivlly worse in a light chop and beats you to death. If you hit any type of wake at speed, 30 to 47 for example, you take to the air and land hard and out of shape. Can tabs tame this thing. As it is, this 16 is no fun at all unless you have near glass water and no other traffic to create wake swells. I am used to driving high performance cars, both on a road course and drag strip. Staying on top of the 16 just wears me out since the boat never seems completely under control.

HELP!

Dave

[gold-n-rod]

Dave, I put several hours on my new (to me) '03 16 Classic today and I can assure you that better rides are ahead.

First, get some tabs. I have to work mine all the time based on wind, waves and speed. Fortunately, I have indicators and they help A LOT!!! Tabs take the porp out of porpoise, right away.

Second, try some other props. Everything I have read seems to lean toward every 16 responding differently to different props. Don't be afraid to experiment.

You WILL get her dialed in, it just takes patience. Good luck.

[BERTRAM BOY]

I would try some props first before I driled holes in my transom a mounted trim tabs.
I have a 16, and It NEVER needs, nor does it have tabs.
Landing "out of shape" is usually indicative of prop blades with too much suface area or too much cup.

Tabs will undoubtedly help, but with the power your running, you really shouldn't need them. I think you would just be masking the problem.

There are plenty of props out there that will fit your drive, so you shouldn't have any trouble finding any.

Also, have you tried a 4 blade? Hydromotive makes a great product.

BERTRAM BOY

[Bad-Tat]

Dfun,
Try raising your trim on the drive. Your note says full trim down. Pull it up some and you should have a much better ride. I agree with Bertram in not really needing tabs. My 16 didn't have them and was very stable at 55 in any kind of water. Trim up a bit and hammer the throttle and you should be smiling soon!

[MOP]

I fully agree with Cliff that for guys that run a 16 hard, have seat time and the right prop they can do without tabs. But for the average Joe that wants a sporty ride does more cruising then hammer down running they are indispensable, they will eliminate the porpoise at cruise, level the boat side to side to compensate for passenger weight and in bad chop take the slamming out the difference is amazing. Do I run hammer down damn sure maybe 10-15% of the time and that may be a high estimate. I boat in a really big bay and do a lot of long runs 25 to 40 miles one way, there is no way can you make runs like that and stay at high speed to much traffic and way to many wakes plus I respect my machinery more then that. On runs like that I ran my 16 at 28-2900 giving me a little over 30 mph, the one time I did do it before the tabs it was one of the most miserable rides I had in any boat. Tabs were the absolute best improvement I made to my 16, without them I had to run under 2600 or over 3600 the 1000 in between was nasty like riding a hobby horse. Many people buy a Donzi for its looks and to use it more as just a run about these are the people that need tabs to be able to fully enjoy the boat and not get disenchanted by its ride and end up selling it. Dave some seat time will also help you to learn some of the handling tricks to get through rough stuff without killing yourself, use the search button up top and you will see far more agree that the 16 out of all of the Donzi boats benefits greatly from tabs.

Phil

[mattyboy]

seat time not stained seats :tongue:
http://www.donzi.net/forums/attachment.php?attachmentid=1404


learn your boat and you can fly too but maybe not get so high ;)
http://www.donzi.net/forums/attachment.php?attachmentid=4896



props baby get u self some props

[glashole]

The only way to love that boat is to get out in it as much as possible and experiment

This is best done by yourself when you have time to kill so you don't have to worry about the passengers or their comfort if it gets a little out of hand.

you will come to learn how awesome that boat can be :)

[gold-n-rod]

Also, have you tried a 4 blade? Hydromotive makes a great product.

BERTRAM BOY

Dave: BB is on to something. Yesterday, I was running a 3 blade 14 x 19P prop and today I tried a 14.5 x 20P four blade (a Mach Sterndriver).

It was like the difference between night and day. It's a little slower to plane, but runs to 4800 at WOT and the dash speedo said 58. Handling was much improved and the attitude of the boat on the water was much improved.

As has already been said, try out some new props.

[dfunde01]

Today's run went better on swmoother water. Giving it a little trim (very little) seemed to help. I am concerned that I am showing GPS speeds of 44 to 47 from 2800 to 3100 rpm.. I either have an exceptional 16 4.3 or have a tach problem. If the tach was set improperly I think I would be reading 50% of actual. I am still 5 hours away from doing some WOT runs, but I don't see it getting anywhere near 4800 to 5000 with the 21P VENGENANCE SS prop. The bilge pump kept cycling on and I found a small hose (1/4 to 1/2") had popped off a fitting under the starboard manifold and was allowing water into the engine bilge. Snapped it back on with no problem.

I am considering a hydromotive or Solas prop. Comments and recommendations will be appreciated.

Dave

[BUIZILLA]

You might want to get ahold of BigGrizzly here on the board. He is local to you, and has access to Solas inventory. I am SURE he can help you with your woe's.

Jim

[Rootsy]

i've said it before, i'll say it again... unbolt the vengence and drop it overboard... get out your paddle and canoe your way back to the dock... go get yourself a 3 blade turbo 1, 4 blade hydromotive quad IV O/T, etc... you will be MUCH happier with the boat...

my 16 ran 54 mph with a 350 bone stock... OUT OF CONTROL AT 54 mph with a 19 vengence... the mirage was WORSE yet... the boat literally frightened me a time or two.. that is a difficult thing to do.

i've run 81 mph in my 16... with one hand on the wheel and about 1/20th the instability of BONE STOCK with the vengence... I have NO tabs, i never have and i never will...

i run a quad IV O/T on a shorty alpha SS... so you cannot souly base a "normal" 16 off of my setup... the O/T will give more lift than the straight QIV and is smaller diameter, the 16's and 18's do not need the big diameter of the straight QIV

cleavers are exceptionally stable and exceptionally fast but mid range cruise BLOWS...

trim the boat OUT until your gps indicates you are loosing speed then tuck it in just a tick and you are at optimal trim... you will feel the hull loosen up, rpm climb and the boat will just sorta bobble over the waves...

JR

[gold-n-rod]

Today's run went better on swmoother water. Giving it a little trim (very little) seemed to help. I am concerned that I am showing GPS speeds of 44 to 47 from 2800 to 3100 rpm.. I either have an exceptional 16 4.3 or have a tach problem. If the tach was set improperly I think I would be reading 50% of actual. I am still 5 hours away from doing some WOT runs, but I don't see it getting anywhere near 4800 to 5000 with the 21P VENGENANCE SS prop.

The tach should have a switch on the back for either 4, 6 or 8 cylinders. You may want to crawl under and see where it is set. My $$ says it's not set at 6 cyl.

:bonk:

[MOP]

I agree with all the porp talk and know full well that for high speed running the right prop is a must but it does not address the poirpoising that he is un happy with at cruise and is a well know problem with all 16's. There have been tons of posts addressing it, true due to the lighter V6 he may get away with a Dolfin to help with the problem. But that will not allow him to level the boat side to side to correct for passenger weight or give him the cotroll needed to run in a bad chop. You can not controll the waves with a prop and not everyone likes to sit exactly where you want them to so the boat rides level.

Phil

[gold-n-rod]

I agree with all the porp talk and know full well that for high speed running the right prop is a must but it does not address the poirpoising that he is un happy with at cruise and is a well know problem with all 16's. There have been tons of posts addressing it, true due to the lighter V6 he may get away with a Dolfin to help with the problem. But that will not allow him to level the boat side to side to correct for passenger weight or give him the cotroll needed to run in a bad chop. You can not controll the waves with a prop and not everyone likes to sit exactly where you want them to so the boat rides level.

Phil

Phil: I agree. It appears that porpoising is an issue endemic to most 16's. A few boats seem to be able to just blast through it, but it depends on how its used. My 16 porpoises like a crazy whore on a trampoline, but a couple of quick taps on the down tab buttons stops it right now. Others may have none, due to the hook in the hull, weight placement (including batteries), outdrive type, engine weight, type of prop and other variables. Dave should not be discouraged from going with tabs. He will NOT be sorry (based on my experience, YMMV).

[Rootsy]

my 16 doesn't porpoise, even with the shortie... it sure as hell did with the vengence and a mirage... the only time i get porpoise is when the boat is following the waves at slow speed. PROP PROP PROP...

[John W]

I had a 2004 16 with the V8, porpoised horribly unles you were going 40 mph. I changed to a turbo 1 22 p prop and added tabs. Was like a brand new boat. In the end I now have the 22 classic and happy kidneys. Much more chesapeake bay friendly.
JW

[dfunde01]

my 16 doesn't porpoise, even with the shortie... it sure as hell did with the vengence and a mirage... the only time i get porpoise is when the boat is following the waves at slow speed. PROP PROP PROP...

I'm sold. new prop it is . Looks like the Qudramotive or Solas are the best choices for max stability from what I have been able to read. About 4 more hours of breakin before I can get some WOT RPM and speed readings to decide on the pitch. I sent Grizz a PM a week or so ago and haven't heard back. I'm talking to one of the guys at Hyrdomotive and he is waiting for WOT data before he'll make a recommendation on pitch.

[Rootsy]

I'm sold. new prop it is . Looks like the Qudramotive or Solas are the best choices for max stability from what I have been able to read. About 4 more hours of breakin before I can get some WOT RPM and speed readings to decide on the pitch. I sent Grizz a PM a week or so ago and haven't heard back. I'm talking to one of the guys at Hyrdomotive and he is waiting for WOT data before he'll make a recommendation on pitch.

Just so ya know... Throttle-Up is much more pleasant to deal with, have great service, knowledge adn are going to be extremely helpful... AND they'll sell you a hydromotive (or have hydromotive send it to you) CHEAPER than hydromotive will sell you a hydromotive...

J

[joseph m. hahnl]

I'm sold. new prop it is .

i say thats the right way to go. get the boat to handle with out the tabs and then add them after for when burger boys in the passenger seat.

ps: I believe that high speed cavitation is the root of porpoising and getting the right prop should make all the difference

Joe

[Forrest]

Before I went with the Alpha SS on my '72 16, I had a ton of mid-speed porposing. I think that part of the overall performance problems with most 16 Donzis is the the drive is mounted too low in the water from the factory. Yea, the 16 is very prop sensitive, but if they would mount two to three inches higher, I think it would make all the difference. The only trouble is that you would probably run into engine hatch clearence problems with the engine mounted that high.

[gold-n-rod]

Before I went with the Alpha SS on my '72 16, I had a ton of mid-speed porposing. I think that part of the overall performance problems with most 16 Donzis is the the drive is mounted too low in the water from the factory. Yea, the 16 is very prop sensitive, but if they would mount two to three inches higher, I think it would make all the difference. The only trouble is that you would probably run into engine hatch clearence problems with the engine mounted that high.

The knob that holds my engine cover/air filter in place (bone stock 5.0 mpi) is rubbing on the underside of the engine hatch. The hatch would have to be scooped or raised (like the 18) at least the height the engine/drive is increased.

[Formula Jr]

For some people here, we will have to agree to disagree about the tabs. I think they are NECESSARY for a 16 and an 18. And if I see a boat to buy and it doesn't have tabs, that is a discount.
Rootsy, if you run 81 in a 16 with out them, my hat is off to you! Given that hull, I don't even know how that is possible. But please guys, lets not get in a flame war over the purity of no tabs. They are an option. Tabs have saved my ass in certain sea states. The correct prop doesn't fix a 40 mph cross wind.

[joseph m. hahnl]

[QUOTE lets not get in a flame war over the purity of no tabs. .[/QUOTE]

i don't think any body was downing trim tabs there point was with the right prop the boat should be able to handle with out them.

joe

[Rootsy]

For some people here, we will have to agree to disagree about the tabs. I think they are NECESSARY for a 16 and an 18. And if I see a boat to buy and it doesn't have tabs, that is a discount.
Rootsy, if you run 81 in a 16 with out them, my hat is off to you! Given that hull, I don't even know how that is possible. But please guys, lets not get in a flame war over the purity of no tabs. They are an option. Tabs have saved my ass in certain sea states. The correct prop doesn't fix a 40 mph cross wind.


FJ... yes you read the speed correctly... 81.3 mph GPS... i have a gps photo at about 76 mph somewhere... first run out with the SS and a cleaver... i tell ya what... it is the alpha SS... and the 4 blade, all the way... seriously... she just flies... and if i am not mistaken there is a crazy canuck here on the board that once had a twin turbo'd 16 that went in excess of 90?!?!?! :shocking:

the ONLY time i might want tabs... is when i am VERY light on fuel and i am in 3+ foot seas... like st. clair in the afternoon headed in at a slow headway... other than that... no need, really....

JR

[MOP]

my 16 doesn't porpoise, even with the shortie... it sure as hell did with the vengence and a mirage... the only time i get porpoise is when the boat is following the waves at slow speed. PROP PROP PROP...

Jamie a boat with a shorty will reduce or eliminate the inerrant 16 problem, a shorty has less leverage It has the same basic effect of raising an OB up a few holes. 16's have and always will porpoise between 28-3500 RPM, it really sucks when you have friends aboard trying to show of you wonderful 16. There are tons of posts and it is more then a well known fact the 16 has a problem that can not be cured without tabs. Sure you can run faster and you will not have the problem but some like to cruise ant times, I owned my 16 for three years and no way would I own another without tabs. This problem has be hashed and rehashed always ending with the same results the boat needs tabs to be cruised, it does not need tabs if you run fast not everyone likes to or can run fast all of the time. Different strokes for different folks. This poor guy will buy a prop only to find out that if he wants to cruise the boat it will still have the problem even more so when carting friends as the 16 porpoises worse with rear seat passengers. Just a sampling of 16 tab posts below.

Read post #8
http://www.donzi.net/forums/showthread.php?t=35616&highlight=trim+tabs
Read #3
http://www.donzi.net/forums/showthread.php?t=34492&highlight=trim+tabs
Read #9 One of the air borne shots in this post
http://www.donzi.net/forums/showthread.php?t=1452&highlight=trim+tabs
Read #6 #7
http://www.donzi.net/forums/showthread.php?t=1630&highlight=trim+tabs
Read #3 #4
http://www.donzi.net/forums/showthread.php?t=1336&highlight=trim+tabs

Phil

[Rootsy]

phil,

you forget i ran a long leg for 3 years....

[MOP]

phil,

you forget i ran a long leg for 3 years....

Jamie you have to admit you know pretty much one speed "hammer down", when was the last time you took a nice easy long cruise? Tabs are for the guy that wants a decent ride at lower speeds. The boat absolutely sucks at 30 MPH especially with rear seat passengers, for skiing, choppy water and the porpoise issue they are a must for the average boater. You forget I have probably installed at the very least a 100+ sets on all sizes and type boats never ever had a customer say anything but good about having them. No argument on a good prop adding stability and handling, but it will little to nothing for the known inherent problem of the 16, when I bought my 16 it had no tabs I tried fooling with props then added the tabs due to recommendations on this board! I really think you are confusing the issue of two types of driving needs or wants.

I read initial post as wanting something different from where the post has gone, maybe I am wrong and he does want to run fast most all of the time. The way I read his post is he would enjoy some nice relaxing riding also, that is not achievable without tabs.

Qoute! Below 2800 - 3000 rpm porpoising gets progressivlly worse in a light chop and beats you to death. If you hit any type of wake at speed, 30 to 47 for example, you take to the air and land hard and out of shape. Can tabs tame this thing. As it is, this 16 is no fun at all unless you have near glass water and no other traffic to create wake swells. I am used to driving high performance cars, both on a road course and drag strip. Staying on top of the 16 just wears me out since the boat never seems completely under control.

Maybe it is time for Dave to jump in and tell us what his boating style is!

Phil

[MOP]

And you (MOP) also forget there are people on the board here that run 22's W/O tabs, and some that can't....

It all depends upon your comfort level...

How can I forget my 22 has no tabs, did not need them ran great with the old setup but may now unless I dump the BH time will tell. A 16 is a totally different boat, I think the 16's hook adds to the problem.

[Greg K]

A 16 is a totally different boat, I think the 16's hook adds to the problem.

Anyone?? :banghead:

[dfunde01]

Maybe it is time for Dave to jump in and tell us what his boating style is!

Phil[/QUOTE]

My style of boating? In my 24' pontoon / 50 hp Yamaha WOT most of the time.

In the 16 I don't really know yet. Until I feel in control of the pup at the high end I won't spend much time there other than to learn. I would like the ability to cruise at 20 to 30 mph without getting beat to death. Since I have no small friends, and the 16 has a 600 pound passenger limit, most of the 16's time will be with two people on board.

My plan is to dial in handling with a new prop and them add tabs to finish the job if needed. In any case I have budgeted for both.

Once again. Thanks for all of the shared experience.

Dave

[Rootsy]

Jamie you have to admit you know pretty much one speed "hammer down", when was the last time you took a nice easy long cruise?
Phil

I donno bout ya sometimes phil... but i i've logged about 300+ miles of "easy" 3000 - 3500 rpm cruising on lake cumberland alone... my engine has spent less than an hour at WOT in it's life... hell most of the time i spend at idle going in circles around small lakes here in the hills with a cup of coffee and my feet popped up on the deck... :rolleyes:

JR

[mattyboy]

Jamie, you damn young hot rodders :) :D how come when I am looking for the air shots of the 16 I don't have one of Jamie??? all the shots I have of him underway must be when he has the coffee :) Phil ?????????? what goes on in there????

I have a non trimable drive and tabs on my 16 with my old prop I found the tabs helped ride stop porpoise since i have gone to the ultra prop the tabs are up and rarely used
now since my boat came with them I did not get the pucker factor of drilling holes in the transom, and I don't know diddley on a black drive with trim
oh and my driving style is just on plane 23-3000 rpm with ocassional high speed run when I am alone or when the kids need to go ;)

Dave I think you are on the right course dial in a prop then decide if tabs are necessary

and you said the "P" word we'll only put up with that kinda language once in the performance section ;) :D shhhhhh don't tell anyone but I've been seen on a 'P" boat on ocassion of course it has no tabs :tongue:

here's a shot of Jamie with the hammer down :rolleyes: I mean his coffee
look mom no porpoise

[Rootsy]

here's a better shot of the "hammer down"

http://www.donzi.net/forums/attachment.php?attachmentid=3508

[mattyboy]

after your coffee???? ;)

where was that shot when I did the 16 tribute ????

[BERTRAM BOY]

Matty,
I think you need to do an updated 16 tribute. I've got some pretty cool shots too.......

[MOP]

I donno bout ya sometimes phil... but i i've logged about 300+ miles of "easy" 3000 - 3500 rpm cruising on lake cumberland alone... my engine has spent less than an hour at WOT in it's life... hell most of the time i spend at idle going in circles around small lakes here in the hills with a cup of coffee and my feet popped up on the deck... :rolleyes:

JR

Jamie I do apologize to you I should not have directed my comments at you :bighug: , got caught up in the issue :rolleyes: . I do stick by my comments about the 16. Heck it has been about two years since I gave the pot a good stir, what would life be if I did not perk things up with some of my Tactful Posts!

Sincerely
Phil

[Sam]

I love it, how about a group hug :D .


Your Humble Servant
Sam

[dfunde01]

I must say that I believe that the color scheme of Jamie's 16 is the most attractive and sporty offered by Donzi ;>). Now I just have to beat myself to death for another 5 hours before I can get some WOT runs to decide which pitch prop I need to try first. I may go for some seat time next Monday or Tuesday on Lanier. Anybody around Lanier got some loaner props that I can test with? 4.3EFI with Alpha I.

Dave

[MOP]

2 years????

My Arse...

Phil, whens the last time you had your sundial calibrated??

Amen! Yup I admit to being a Crusty Old Fart, it comes to all as you aquire time in grade!

[mattyboy]

2 years
wow it seems like only yesterday :rlol: :) :D hehehe

[boxy]

2 years
wow it seems like only yesterday :rlol: :) :D hehehe

Now I don't care who you are, that 's funny......

[Rootsy]

1.75 months.. 193 to go... and someone owes me some beer :D

[boxy]

You've got to show up to collect.

[Rootsy]

You've got to show up to collect.

you need to go do some more reading in another chapter pal... :rlol:

[Greg K]

just some more 16 bottom pics..

[dfunde01]

One more problem solved. The tach was set on 8 instead of 6. Now I have to track the fuel gauge problem and dial in the right prop.

Dave

[gold-n-rod]

The tach should have a switch on the back for either 4, 6 or 8 cylinders. You may want to crawl under and see where it is set. My $$ says it's not set at 6 cyl.

:bonk:

Ding, ding, sounds like we have a winner!!!!