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View Full Version : Handling issues/rpm question on 1995 16C



skifastinvt
06-28-2008, 10:50 PM
Hey everyone,

I spent my first full day on the water with my "new to me" 16 classic. It's 1995 with 4.3/alpha one. Stock setup with stainless prob. No tabs. I've read all about the listing to the port (when you have someone sitting on that side), porpoising, and tricky handling. I will agree with all of those comments. Prior to my Donzi, I owned a 16 Glastron Carlson outboard. The Glastron didn't have any of these handling issues (zero porpoise issues ever), but it didn't run 55 mph either! My biggest concern is the porpoising between 25 and 35 mph (it pretty much disapears over 35mph). I want to be able to run the boat with passengers on a slow cruise or tow a wakeboarder. The porpoise isn't ideal, and can old really fast. I know trim tabs are an option (would rather not spend the $). Have any of you tried a bolt on hydrofoil/doelfin? I've always thought they were a gimic, but some people seem to love them. Any Donzi experience before I run out and drop $50?

One last question. For those that have a 4.3....what RPM are you spinning at WOT? I'm at about 5200 RPM. I know outboards are designed to run at high RPM's. How hard do you guys run your i/o's?

Thanks in advance.

Alan

BigGrizzly
06-29-2008, 09:24 AM
Trim it down then slowly trim it back up. Remember at that slow speed anything can set it off. Below 35 is a problem, but manageable because of the rocker hull. REMEMBER, it will take a while for the Proposing to stop,then trim it back up. Every speed has a different trim angle. This is a driver's boat. The Carlson is a good unit but a different class.

MOP
06-29-2008, 12:31 PM
Add to Randy's input put tabs on it, it is one of the few Donzi's that tabs are a must. I had my 16 for 3 years and absolutely loved it once I put the tabs on, before it was a pain and many times no angle of trim helped. Before tabs I ran it slow or fast very little in the middle as it felt like a hobby horse!

gold-n-rod
06-29-2008, 01:36 PM
I want to be able to run the boat with passengers on a slow cruise or tow a wakeboarder.

You bought the wrong boat.

MOP
06-29-2008, 02:56 PM
I would not go that far as to say wrong boat, he needs tabs and another prop for pulling power. Not sure what prop is on there now, post it's size and you current top RPM. There are quite a few V6 16's that are doing what you want to do, you just need a little setup.

Phil

mike o
06-29-2008, 03:32 PM
You bought the wrong boat.
I have the same exact boat as ski fast . I kinda like the way my 16 is so lively with out trim tabs. Its like a race horse. I was drouling over the 383 down south myself. But I guess the govenor of N.H. is going to sign the 2 yr 45 mph speed limit bill on WINNI and with the 92 deciable limit, and switchable exhaust illegal here in the live free or die state. Selling the 4.3 and Driving to Naples aint gonna happen. 72 mph sure would be fun..... kinda suprised is still around. O-WELL. gonna try laser II 25 pitch.... let the 4.3 rip

gold-n-rod
06-29-2008, 03:42 PM
The 16 is not a low speed crusier and/or towboat. Sure, you can throw a bunch of money at it and get it to do those things, but...

1. The OP doesn't want to spend the money.
2. He wants his cake (top speed) and to eat it (towing power), too!

That's why I said he bought the wrong boat. It's like saying, "I just bought a Fatboy and it's not very good on the trails. How can I spend $50 and make it a better trail bike?"

MOP
06-29-2008, 04:25 PM
I just noticed the hydrofoil/doelfin thing forget it on a 16, the guy that owned mine had one on for about two weeks then got rid of it. Problem is as you trim up the fin starts to dive and suck the stern down, was a very weird thing and was a lot worse with passengers.

If you are spinning 5200 leave the alone that engine is happy down to 4200 WOT. Break down and buy real tabs, the 16 is faster same RPM at mid range with tabs as it is not hobby horsing you will not regret it and increase the boats value a bit.

Phil

skifastinvt
06-29-2008, 08:03 PM
Thanks for the thoughts everyone. I think Gold-n-rod might have misunderstood my intent. If I wanted a tow craft, I would have bought a Mastercraft. I am however looking for a bit more flexibility than 50+MPH or nothing single seat PWC. Everything that I have read and heard point to trim tabs. I might make the plunge this winter, but I want to get to know my boat before I apply a "bandage"

I read a few replies about messing with the trim to reduce porposing at 25-30mph. I just don't see how trim would effect this. I will get the porposing with the trim all the way down. I would think that trimming up at low speed would just force up the bow and make it worse...but I'll continue to play with it. Thanks for the advice on the doel fin/hydrofoil...I didn't think it would help.

I will say, the boat seems to run better (less porpoise, and runs with less list) with just me in the boat. A few of you might be reading my posts and saying this guy is a idiot. Learn to drive a boat, "you bought the wrong boat", etc. As I said, I have owned a 16 glastron carlson that will do 50mph+. It drives much differently (in some ways good, some ways bad), but I can assure you, I am not a novice boater. I'm excited to learn more about the Donzi, but I am somewhat surprised/disapointed that the design requires the use of tabs to run correctly. Again..I'd love to hear some thoughts.

Sweet little 16
06-29-2008, 09:46 PM
I really can not believe that a boat that started it's live as the ski sporter is being thrown under the bus by long time members here???? it travels in the world of tow boat and go fast better than any other boat I know of, the deep vee of the classic as we all know has some handling quirks but the porpoise is strictly a reduntant cycle caused by the prop and it's lack and then re-capture of bow lift comes and goes depending on the prop, as any "classic" prop choice is key, the 16 with trim and the right prop has been clocked in the high 70's with no tabs and in the 80's with a shorty , as all that has been said about the 16 being a drivers boat is dead on do not do anything to the boat until you get the right prop and some seat time ours was a great family boat that did the tow, lounging, and go fast thing very well
anyone who bought a 16 knows it will be the boat they always remember never the wrong boat

skifastinvt
06-29-2008, 10:03 PM
Thanks for the encouragement sweet little 16! I'm sure I need a little "seasoning" to get the handling right. I know the 16 is one of the best hulls ever designed...I too couldn't believe all of the negative thoughts. I have a factory stainless prop on it. I'll have to take a look for exact measure. What do you suggest running on a 16 with a 4.3?

yeller
06-30-2008, 12:16 AM
I had a 16 and didn't need the tabs, but it was a jet drive so handled differently. I used it almost exclusively for skiing and barefooting the 1st 1/2 dozen years I had it. It looks as if you'll have to put tabs on it to do what you want it to. Then you can have your cake and eat it too. Drop the tabs for wakeboarding...raise them for top speed runs. Enjoy it, it's a great ski boat.

Sweet little 16
06-30-2008, 07:51 AM
biggrizzly rootsy madpoodle would be the ones to ask for prop selection on a merc

smbarcelow
06-30-2008, 08:50 AM
I don't have much seat time in my 16 yet, but I found that speeding up beyond the point of porpoising and then backing into a comfortable cruising speed seemed to work fairly well. This was with my trim all the way up (highest pin location on non-trimable outdrive) and two passengers with me.

The Hedgehog
06-30-2008, 09:44 AM
The funny looking fin does work and will elminate the mid range bounce. It will take about 3 mph off the top. They are no big deal and take about 2 min to take off. The better solution for very slow speed will be tabs but the foil works in a pinch. You can also accomplish some better handling with a different prop.

I used a 16 for many years as a ski boat and it was fine. Heck, I even tricked behind it. A good driver is required to keep things evened out at very low speed.

You will be just fine and did not buy the wrong boat. Enjoy the Donzi

BigGrizzly
06-30-2008, 11:03 AM
The 16 is a great boat. My 1966 we still have and doesn't have trim and doesn't have tabs either. ALL rocker hulls porpoise to an extent. Anyone who says theirs isn't telling the truth. I have all three a 16, a 18, and a 22 and they all do to a point, the 22 doesn't have a rocker either. Relax this isn't a outboard. You don't drive them at 16 mph. Learn to drive it and fall in love with it like all of us have! At the lake George event it seamed like the 16s were having the most fun!

VetteLT193
06-30-2008, 01:22 PM
I have yet to own a boat without tabs that couldn't benefit from having tabs in certain conditions. If you are an all around boater tabs will certainly help. there are usually deals on eBay so keep an eye out there.

As far as dealing with the porpoising at slow speeds without tabs: too much trim up or down will cause porpoise. you have to find the right neutral setting

skifastinvt
06-30-2008, 09:42 PM
Had some fun in the 16 tonight. Great comments everyone. They really helped. After driving for a few hours (calm lake with light wind ripples), I really started to get a feel for the boat. I certainly see the need to power up, get the bow down, then back off to a cruise speed. I had no problem backing down to 2800 rpm's and cruising at 20-25mph (kids waterski/adult wakeboard speed). I also did a bit of high speed play (including turns). I found that I get get her to spin about 5200 rpm's and the speedo was pinned at 55. I know that speedo is never right, but I didn't have a GPS with me. I could really feel the effects of the trim at high speed...but the boat did feel super stable in a straight line. Like I said in a previous post, I'm new to the I/O world. I know they don't like to run at high rpm's like an outboard. How hard do you guys run them, and for how long. I feel guilty if I let her spin at 5k for more than 15 seconds! I feel like I'm doing damage.

I'm still amazed how adding a passenger totally changes the handling characteristics of the boat. The combination of torque pull and passenger weight really does make the boat list to the port side. I guess trim tabs are the only way to fix this. Do you think the Donzi was orginially designed as a single passenger boat?

To sum it up, I have discovered why people are hooked. I'll keep learning.

Kirbyvv
07-01-2008, 07:49 AM
I have an 18 so it's different, but I don't use the tabs when I'm by myself, but do us them when I have passengers at times. Keep playing with it. Like someone said "a Donzi is a drivers boat". Takes some time, but once it clicks it's a blast.
Where in VT are you? I'm northern end of Lake George.

MOP
07-01-2008, 07:58 AM
In reviewing this post it is fairly easy to that most of the folks that says tabs are not an improvement do not have them, to form an honest opinion you must experience the change in the boat. The swap for me and many other was nothing short of great! It did a few things, it banished the low speed wag that all deep V's have, it balanced passenger weight and greatly improved runing in bad seas.

Phil

Sweet little 16
07-01-2008, 07:06 PM
In reviewing this post it is fairly easy to that most of the folks that says tabs are not an improvement do not have them, to form an honest opinion you must experience the change in the boat. The swap for me and many other was nothing short of great! It did a few things, it banished the low speed wag that all deep V's have, it balanced passenger weight and greatly improved runing in bad seas.
Phil
the main thing mentioned was the porpoise , the other thing mentioned was not spending money, tabs correct alot of ill's but on a boat with trim and the right prop the porpoise can be tamed this opinion is formed on the fact that our 16 ran atleast 10 props and once the right one (solas) was found the tabs were no longer used on a non trimable old volvo , the boat did not re enter hard to either side no chine walk no torque steer as happens with large eared props the porpoise was minimal and the range it happened was very small and could be eliminated by exactly what has been said speed up onto plane then throttle back to cruise speed, tabs will add some value and all of the things you mentioned and he may find he needs to add them down the road but seat time and the right prop is the first logical step on what may be a long journey of work done to the boat or a short trip onto the next bigger boat honestly the biggest improvement or investment to a 16 is the prop ! it made our's tame enough so that i could drive it instead of my husband all the time with the death grip on the wheel

BigGrizzly
07-01-2008, 07:57 PM
I keep forgetting about the my Solas props. They do give it acceleration and top speed

Sweet little 16
07-02-2008, 07:01 AM
skifastinvt,
the 16 was designed as the name implies skisporter as a ski and sport boat
the hook was put into the hull to help quick planing for skiing not a single passenger runabout. most if not all of the handling quirks can be addressed or controlled with the right prop and the correct trim angle. usually when you find the right prop the rpm's will come under control as well

BigGrizzly
07-02-2008, 09:14 AM
Who sweet little! That is not true. The hook as you call on the lifting strakes were put there for quicker plaining -true but it did not have anything to do with skiing! It had to do with the fact that back in 1964 they put V8s in the boats and they could not cruise at any speed lower than 40mph. When at higher speed they have no effect at all except on wake jumping and re-entry. We once removed them on a friends boat and ended up putting them back, because it handled so bad an there was no increase in speed at all. !8 and early 22 have it also. the newer 22 hulls have a different strake design, that does almost the same thing, it is more like a Volvo Speed rail. Just trying to keep the facts straight. Some people think the Corsican is a ski boat because of the ski lockers on each side of the boat. Nothing can be farther from the truth, they just couldn't find another way to describe them.

VetteLT193
07-02-2008, 09:50 AM
Who sweet little! That is not true. The hook as you call on the lifting strakes were put there for quicker plaining -true but it did not have anything to do with skiing! It had to do with the fact that back in 1964 they put V8s in the boats and they could not cruise at any speed lower than 40mph. When at higher speed they have no effect at all except on wake jumping and re-entry. We once removed them on a friends boat and ended up putting them back, because it handled so bad an there was no increase in speed at all. !8 and early 22 have it also. the newer 22 hulls have a different strake design, that does almost the same thing, it is more like a Volvo Speed rail. Just trying to keep the facts straight. Some people think the Corsican is a ski boat because of the ski lockers on each side of the boat. Nothing can be farther from the truth, they just couldn't find another way to describe them.

Why did Donzi include "A Donzi Built for Skiing is Still A Donzi" in the brochure if it wasn't actually built for skiing?

Sweet little 16
07-02-2008, 09:53 AM
from the 1967 catalogue

BigGrizzly
07-02-2008, 10:14 AM
That was for advertising and hopefully increase sales. Every skier knows a deep V is not the boat of choice especially for getting a skier up. Remember brochures are for sales purposes. Yes I have skied off our 16 for years in the Barnegate bay and in the Atlantic ocean off Point pleasant New Jersey. Then again I also skied off the back of my Jersey Skiff too (what a trip). When was the last time you saw a Donzi in a ski tournament? Once a sales department gets a hold of something all bets are off.

BERTRAM BOY
07-02-2008, 10:33 AM
Alan,
Do you know what particular prop you are using? There are a lot of "factory stainless" props out there, and your description is a little vague. A better description would be more help.

Sweet little 16
07-03-2008, 06:38 AM
Alan,
being your in vermont not sure how far lake winnie is from you but you might want to think about going to their poker run, it would be a chance to tap some knowledge from the people up there and meet some great people, check the event section here for details

another thing to check would be the fin on the outdrive if there is one it is made to help but if it is set wrong it can hurt

The Hedgehog
07-03-2008, 07:42 AM
I would get back to the prop issue if you want better handling. Spend a little time with it and you can get much better results. I went from a Mirage Plus (what the factory uses) on my 18 to a Turbo. The Turbo went just as fast and maybe a little faster but the handling is much improved. It took out most of my porposing. It is a much better prop for that boat.

roadtrip se
07-03-2008, 01:43 PM
and skip the whale tail.

I had a 1996 16 with the 4.3 alpha and the wrap around seating.

It was a heck of a ski and tubing boat. I told Jill that I wanted to see the registration numbers on the nose when I was out there, or she wasn't trying hard enough. We had a ball with it.

I am a big believer in keeping the tabs out of the water unless you really need them. This configuration and generation of the 16 really benefits from having them at all speeds, low, middle, and top end.

The boat will be much more enjoyable and have more utility for all the things that you want to do with it with a set of bennetts. And the bennetts aren't that expensive to buy and install.

Good luck.

skifastinvt
07-14-2008, 11:55 AM
I took a closer look at my prop. last night. I'm not too sure how to read the part number on it, but my best guest would be a 16 inch prop with 23 inch pitch (part # starts with a 16 (size??) and ends with a 23p (pitch??). It's a stainless prop three blade that came with the boat. No brand name on it, so I assume that it is a merc. prop. What kind of props are you guys running on your 16 donzis. I've heard a lot of talk about finding the right prop helping with handling.

Thanks!

Alan

mike o
07-14-2008, 01:02 PM
Hi, cgentile posts will be informative relating to this topic from last yearish. he has the same package as you. Am I correct, that I talked to you last year and you looked at the 16 I bought?