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W.Davis
10-11-2012, 10:51 AM
How would an 18' donzi classic with a v-drive handle compared to an inboard-outboard?

mattyboy
10-11-2012, 01:20 PM
W.D drop a line or pm to board member "flatracer, aka barrelback" he is familar with v-drive 18s

olredalert
10-11-2012, 05:42 PM
----The V-drive has some inherent problems that an outdrive solves. To steer a V-drive you turn the rudder. The propwash is all aimed out the rear except for what hits the rudder. Its inefficient. With an outdrive you aim the propwash and all of it pushes you around the turn. Much more efficient. And,,,when in a harbor at slow speeds there is much less water passing over the rudder surface. Single engine V-drive boats are more difficult to dock than their outdrive cousins. And forget about reverse as then there is hardly any water flow over the rudder surface at all.
----Add to that,,, most outdrives, certainly all the new ones, have power-trim. With trim you can get maximum performance by lifting as much hull out of the water as you can. Works well in a straight line. V-drives are slower because they have more wetted hull and wetted hull kills speed......Hope this is what you are looking for.........Bill S

silverghost
10-11-2012, 05:58 PM
I know my post may open up a "Can of Worms" among V-Drive Donzi owners.

But in my experience with conventional shaft inboards, V-Drives, & I/O powered boats I know that the I/O drive boat will be quite a bit faster with the same horsepower, and steer much better at slower running & docking speeds.

The inefficient fixed shaft & propeller angle of 11*-15* , along with the long shaft, big rudder, and shaft strut also results in increased drag, and is one cause of the lower speeds for V-DrIves , & straight conventional inboards.
Old time boat racers used very long propshafts to decrease the under boat shaft & prop angle.
This helped a bit~~~but realistically how long can you really make the propshaft in a Donzi 16 or 18 ?
An I/O prop pushes basically at a very low angle almost straight aft , and can be trimmed buy moving the transom unit's fixed drive angle pin, or hydraulic trim cylinders. The I/O propeller angle is much more efficient & thus faster for the same basic engine horsepower.
A single straight inboard, or V-Drive, won't reverse steer worth a darn as it will always pull hard to one side directon in reverse (transom walk) no matter the rudder's steering angle; due to reverse prop torque steer & the reverse thrust water hitting the bottom of the hull on one side.

NOTE:
I have never owned a V-Drive Donzi.
But I have owned several V-Drive Chris~Craft Lancers & literaly a dozen++ + straight "Old School" Mahogany woody conventional single inboard drive speedboats over my lifetime.
In Fact~
I now own a straight inboard Big Block Chevy American Skier Super Eagle 24' skiboat which I love !
I also have several hundred hours seat time in my late younger cousin Bobby's early yellow fiberglass Century Arabian speedboat which had a V-Drive/ reverse mounted Chrysler 426 Hemi coupled to a Borg Warner Velvet Drive silent morse-chain tucked under engine V-Drive . The Century Arabian has a similar aft engine compartment & engine configuration; as well as being of similar length & beam of a Donzi 18.
The Arabian's V-Drive's under boat prop shaft angle was also similar to the V-drive Donzi 18s.
The Century Arabian had a V bottom that slightly flatened out at the aft bottom's stern unlike the full deep V of the Donzi 16 & 18 hulls.
It was a fun little "Old School" V-drive speedboat !
I believe the Century Arabian has been sitting gathering dust, & unused, in my Uncle's industrial park storage building for the last 25+ years since my cousin Bobby was tragically killed at age 19 from a massive head injury suffered in a motorcycle crash..

Bob
10-11-2012, 09:15 PM
About the only plus for v drives is that the reliability is great and the servicing is easy, cheap and simple.

Conquistador_del_mar
10-11-2012, 11:24 PM
I had a v-drive Donzi 18' Corsican with a BBC. I will never own another v-drive. Many of the negatives have already been pointed out - add the fact that you can't trim up in shallow water. I once idled into a tree stump. The only way I could get the rudder dislodged is by jumping on the bow - just like removing an axe - lol. Bill

To better answer the question, mine handled fine once running with no particular steering torque, but it was horrible in the marinas.

Ghost
10-12-2012, 01:59 AM
In short, badly. Compared to an I/O, it's nearly all downside, as has been pointed out. I wouldn't touch a v-drive in any configuration but twins, and even then, I'd rather have sterndrives. (Except in a raceboat. ;) )

silverghost
10-12-2012, 02:18 AM
If your boat will actually stay sitting in the water, (especially saltwater), all season long for six+ months~~~you should possibly consider an "Old School" V-Drive Donzi.

This is exactly why my primary everyday saltwater boat is a conventional "Old School" inboard skiboat with a FWC inboard engine.

Scott Pearson
10-12-2012, 05:39 AM
Yea....But they look kool as hell!!!!!!:biggrin.:

Just Say N20
10-12-2012, 06:20 AM
Well, that one does, for sure! But it has a LOT of extra goodies on the transom compared to every other V-Drive Donzi I have seen.

Definitely a very high cool factor the WA-LO.

mattyboy
10-12-2012, 06:21 AM
I'll preface this with I could never own a v drive my local water conditions change to much.
yes around the docks or stumps they are a bear, but I saw Pearson with all that HP and blower surge handle the v drive without issue and to tell you the truth I was expecting an oliver stone " back and to the left back and to the left" with dock rash . that never happened.

the reason I said talk to flatracer he has the v drive in the same hull that you are looking at and I think he sees the same or close to the same performance with an I/O hull running the same power. I also think he found that some of the harsh ride chartacteristics that the I/O version has are not present in the vdrive version.

mattyboy
10-12-2012, 06:52 AM
hey sometimes they don't need all the cuisinart stuff to look cool sometimes less is more with out that big ugly OD sticking out the back ;)

http://gallery.lgdonziclassic.com/main.php?g2_itemId=1583

olredalert
10-12-2012, 10:57 AM
----In my post above I neglected to say that the V-drive 18s corner like they are on rails. There is a local V-drive Corsican that I had a ride in about 5 years ago powered by its original 427 HM and at full speed the owner made a very abrupt right turn. Scared me to death but the boat turned on a dime......Bill S

silverghost
10-12-2012, 12:14 PM
Bill S `~

A V-Drive, & conventional straight "Old School" inboard, sure do have a uinque feel to their ride.
They are very stable and many do corner, turn, and act like they are on rails.
The I/O drive boats have a totally seperate and unique feel that can best be described as much looser.

Brownie was one of the very last builder/designer/racers to convert to I/O drives.
He still liked, & hung onto, the "Old School" V-Drives & straight inboards long after others like Don Aonow had switched to the then new outdrive drive systems.

You just have to know, & accept, the limitations of these "Old School" V-Drives & conventional inboards.
I have been driving these "Old School" simple drives all my life.

Ghost
10-12-2012, 12:22 PM
My experience in cornering is that if there is any greater stability in v-drive boats, it is a function of their MUCH larger, rudder-driven turning radius. The exception to this is boats with a midship skeg, like competition ski boats. These can corner on a dime compared to rudder-only boats, in my experience. Similar to an I/O in turning radius.

I also don't know to what extent the cornering is related to shallow deadrise, versus deeper v hulls like a v-rve Donzi would be. My v-drive boat was a twin engine setup with a 25.7 degree v. It felt very stable but took REEEEALLLY wide turns. Climbedout the hole like a beast though, with minimal bow rise. But it had 700 cubes and 620 HP in a 25 foot hul with 15 inch-pitch propsl, so that holeshot may be only correlated to, not derived from its inboardness.:) I think ski boats do the same because they're so flat, and similarly low-geared in their propping.

(Of course, if your boat is going to be left in the water, especially salt, I suspect the corrosion-resistance of an inboard might trump all other considerations anyway.)

W.Davis
10-12-2012, 01:58 PM
Thank you all for your inputs I've learned a lot and really appreciate it. Just wondering how it would perform in rougher water? 2-3' chop?

mattyboy
10-13-2012, 04:27 AM
is this a true 2-3 foot chop? the small donzi classic hull handles rougher water much better than other designs in that size range the model that you are looking at is a true sharp keeled vee that once up and out of the water will ride over and cut thru the chop, they actually are faster in mild chop than flat glass water.

the con's brought up here about vdrives are true but the reality is that once under way an early 18 powered by a 200 ish hp volvo aq with no trim
and a vdrive 18 with the same HP perform about the same. The i/o might be a mph or two faster due to less wetted surface but when it gets rougher that wetted surface will help ride and the boat will track and cut thru it and not launch and bounce as much.

the reason I asked about being a true 2 to 3 foot chop is the 18 only has 20 inches of freeboard at the bow a drift or at idle speeds so anything over that will break across the bow. You need to pick a boat that is right for your boating style and water conditions. the 16 or 18 are great lake( not Great Lake Boat) and small bay boats. they will get you home even if it kicks up more than usual. but if you are in 2-3 on a normal basis you might want something with a little more freeboard and LOA like a Hornet or GT or a 22c.
those will be dryer more comfortable rides.

the 18 is good in 1-2 everyday and will be okay in 2-3 but not dry or real comfortable.

hope that helps

mattyboy
10-13-2012, 01:56 PM
the ride shouldn't be all that much different from the Corsican, maybe a little more of an on the boat feel over the in the boat feel from the higher deck and closer seating of the Corsican.

good luck hope it works out for ya

thescooter
10-13-2012, 03:16 PM
i have owned both i/o inboards.
being in boating since 1963 with my father i can say this.
there are plus and minus to both, such as any this in life.

inboard vrs outdrive.

outdrive you can change your prop quick and easy.
outdrive docks easier.

inboard is better in a chop.
inboard is easier and safer for a ski boat.

up-date or complete re-powering is easier with a inboard shaft.
no transom work needed.

a outdrive top end is faster than a inboard shaft boat.
a in-board shaft will get top end faster.

this list can go on and on.
lets see what every one else says
nick thescooter

silverghost
10-13-2012, 05:55 PM
Ghost~

My 24' Inboard skiboat has two large shark fin style bronze skegs located on the keel ceterline just below the ski tow pylon in front of the motorbox .
These two shark skeg fins work together in tandem along with the very large balanced high speed inboard rudder to give this inboard skiboat very tight, & fast, agile stable steering very much like an outdrive boat.

I think adding these shark fin skegs to any V-Drive Donzi would be a great way to improve steering & handling agility.

Perhapps Scott Pearson might consider adding these bronze shark fin skegs to one of his Donzi V-Drive projects ?
I think it might be a very successful, & interesting, experiment.

Glenwood Marine/ Glen-L Designs sells several sizes, & styes, of bronze keel skeg fins. Usually two, or three, are used on a boat.
My 24' American Skier Super Eagle "Old School" inboard skiboat has two mounted on it's keel centerline.

mattyboy
10-13-2012, 10:49 PM
[ QUOTE=$originalposter]silverghost
Shark Fin Skegs
Ghost~

My 24' Inboard skiboat has two large shark fin style bronze skegs located on the keel ceterline just below the ski tow pylon in front of the motorbox .
These two shark skeg fins work together in tandem along with the very large balanced high speed inboard rudder to give this inboard skiboat very tight, & fast, agile stable steering very much like an outdrive boat.

I think adding these shark fin skegs to any V-Drive Donzi would be a great way to improve steering & handling agility.

Perhapps Scott Pearson might consider adding these bronze shark fin skegs to one of his Donzi V-Drive projects ?
I think it might be a very successful, & interesting, experiment.

Glenwood Marine/ Glen-L Designs sells several sizes, & styes, of bronze keel skeg fins. Usually two, or three, are used on a boat.
My 24' American Skier Super Eagle "Old School" inboard skiboat has two mounted on it's keel centerline. {$pagetext}[/QUOTE]


so now we need skegs on a v drive Donzi???? we have just heard from Olered that a corsican v drive turns like it is on rails we need to improve on that? it's been said here vdrives have no trim and have to much wetted surface and drag but now we are going to add more drag??????

silverghost the v drives Donzi covered a few different hull shapes and sizes single and twin configs, can you please give info on which ones you have seat time with as a driver or passenger to support your opinion? can we really compare a 24 foot skiboat with an 18 Barrelback???? are the deadrise and bottom configurations the same or close to the same???

I am sure if you give Pearson a call and give him your research and findings he might add a fin to one of his projects. I am not sure if adding a fin would be interesting but that phone call would be :yes:

BOT
WD test drive the boat if it is something you think fits your boating style and conditions get it ! v drive 18 are fairly rare and should perform reasonably well as long as you are not looking to set the water on fire.

olredalert
10-13-2012, 11:16 PM
----Matty,,,He must have been kidding. He was wasnt he??? Really,,,wasnt he?.....Bill S

silverghost
10-14-2012, 02:30 AM
Mattyboy~

Read Ghost's post #15 above and get back to us.
He was the first to mention these skeg fins & how they improve an inboard & V-Drive turning ability.
A shark fin skeg will improve the handling & steering agility of most "Old School" straight inboard, or V-Drive boats.
Inboard & V -Drive raceboats used them for decades. Garwood, Hacker , Dodge, Chris~Craft, & yes Bownie used them on their raceboats.

You should attend an Antique & Vintage inboard & V-Drive race boat event some time and have a look under some of these famous race hulls.
Guess what you will see there ?
Keel mounted shark skeg fins.

I suspect all these world famous inboard boat racers & desgners All knew Much More about keel mounted shark skeg fins than you Think You Do !

mattyboy
10-14-2012, 06:40 AM
Bill to tell you the truth I have no idea ????????????



SG~~~~

just getting back to you here I did read and now have re-read Ghost's post . Think I have a full grip on what he said, he gave info on competition ski boats and a deep v twin v drive then stated
"I also don't know to what extent the cornering is related to shallow deadrise, versus deeper v hulls like a v-rve Donzi would be" I have no issue with what ghost stated he gave his knowledge on his twin v drive then stated he did not know what cornering would be in a v drive donzi.


the issue I have is with your statement and your normal dodging on the questions put to you. I asked if you had any first hand info or knowledge with V drive donzi to support you statement that Pearson should put skegs on his vdrive project. we are not talking about a 24 foot ski boat or a flat bottom woody or a vintage race boat. WD asked about a v drive 18 true v sharp keeled boat not any of those other boats.

I have never been in a v drive corsican but when Bill says they corner and turn on a dime I'll take his word on that. He has ben around Donzi for a long time and also has owned several different models . so he is a good benchmark when it comes to comparing models and rides. I have seen a few vdrive donzi and been in one and I was a bit surprised that the ride is not all that much different from an I/O but that could be just more of a perception thing on my part. i thought they would drive and ride more like a woody or ski boat sort of plowing along they don't.

thanks for the advice but I have a fair amount of time at acbs shows( i actually won an award how did they let that happen?) and have visited clayton and mystic several times now. I know that fins help ski boats and flatter bottom
boats turn .

again why do you think this and what support do you have for this statement

from your post

"I think adding these shark fin skegs to any V-Drive Donzi would be a great way to improve steering & handling agility.

Perhapps Scott Pearson might consider adding these bronze shark fin skegs to one of his Donzi V-Drive projects ?
I think it might be a very successful, & interesting, experiment."

WD keep us posted if there is anything i can help with let me know good luck hope this works out for you

BUIZILLA
10-14-2012, 07:14 AM
if it would have helped a V to have a fin it would have been done 80 years ago and been a life staple at this point in time..

and, it isn't

Scott Pearson
10-14-2012, 08:50 AM
WA-LO does not corner very well. You need to take very wide turns. I'm not sure about the 427 V-Drive Corsican that I have....its not done yet and will be ready maybe end of next year. I would think they would be both handle different...Bill has my interest now on how the Corscan will handle...Cant Wait!!

It is a bit hard to dock WA-LO with the V-drive but I'm sure like Matty said that the Blower Serge and the HP dont help. I just take my time coming in to dock. It pretty much has a mind of its own.

I better get use to it quick! I now own 3 Big Block V-Drive boats...no turning back...

olredalert
10-14-2012, 09:12 AM
----Lets see,,,Jim Wynne, Walt Walters, even someone as smart in todays yacht, go fast, and ocean race boat world as Michael Peters have not found a need for any bolted on appendages attached to their hulls, but you have???....Bill S

Just Say N20
10-14-2012, 10:00 AM
Oh no. . . .

:popcorn:

OFFSHORE GINGER
10-14-2012, 02:58 PM
There was a time a few years back when i was with Skater we were adding more then a few Fins / Skegs or Keel Daggers as we called then to 40's & 46's to assist in the turns on the coarse .

mattyboy
10-15-2012, 06:13 AM
Ginger
yes I have no doubt that fins on the sponson of a cat or tunnel hull will help it corner

something like these fins/rudder on canadian girl.

http://www.vintagehydroplanes.com/boudreau.html

my point or theory here with what I think are supporting facts or info.

anyone that has driven a donzi classic or other deep vee runabout know in a turn the boat will roll onto the side of the turn and carve the turn then when coming out will level out. the reason the hull has two sides of the V . flat bottom boats only have one side the bottom so they can't carve a turn with out a knife to help them ( the fin).

cats and tunnel hulls have two sides but due to their design can't drop one sponson down and get the other one up ( anytime I have seen that it has not been good) they take the turn level so to avoid skidding/skipping the also may benefit from a fin.

As I mentioned before the donzi classic hulls varied in shape and size all deep V some deeper and sharper than others so to make a blanket statement that covers them all is inaccurate. The boat WD is looking at is a 24 degree sharp keeled boat. wa-lo is a wider, rounder, flatter bottom the same bottom as my boat which still rolls onto it side and carves a turn well. I spoke to Scott and we feel it is the exhibit from the precious metals museum on the back of wa-lo , not the fact that it is souly due to being a v drive. The tabs on the cav plate are huge and come into the centerline of the boat much more than normal tabs would.we feel that these are keeping the boat from rolling onto it's side making cornering difficult. they are setup to give the boat a better ride angle and getting the most of all the power being sent to the water in a straightline but might hurt cornering. We will see when the corsican and the ultimate hit the water. we should have a good cross section of data on v drive classics then.

OFFSHORE GINGER
10-15-2012, 12:12 PM
Matty , easy guy........................... because all i was doing was making a statement on this thread concering the fins or keel daggers and the reason why we put them on Skaters with out trying to go into theory or depth about the subject , and if i took your last post the wrong way i apologize because it is not a very big deal to me ( subject ) if you know what i mean . ;)

mattyboy
10-15-2012, 12:33 PM
Ginger. Not a problem :). I had no problem with your post. Or the info in it

OFFSHORE GINGER
10-15-2012, 12:52 PM
Matty , its all good and the fin / keel dagger's we put on Skater's where not stationed on the back of the Sponson's like Canidian Girl .

Scott Pearson
10-15-2012, 02:36 PM
Im going to glue a Keel Fin to my life vest and see how that works......LMAO:cistineb:

BUIZILLA
10-15-2012, 02:46 PM
http://www.stuntsteel.com/assets/images/helmets/green-helmet-mohawk.jpg

mattyboy
10-15-2012, 04:12 PM
Scott this would work plus it would keep your hair from blowing around

W.Davis
10-16-2012, 12:33 PM
Hey guys sorry for all the questions, I'm a little new at this but if I added trim tabs to an 18' V-drive would this help get the bow up a little and provide less hull to be in the water for some more speed?

Just Say N20
10-16-2012, 12:44 PM
Trim tabs are used to force the bow of the boat down. While they can slightly add to the running surface, I don't believe they will help get more of the hull out of the water.

MOP
10-16-2012, 02:02 PM
The only thing that will help in lifting the bow is Arneson Rocker plates, a fairly expensive option. My take enjoy the reliability which is may fold over an out drive!

W.Davis
10-16-2012, 03:14 PM
Thanks for clearing that up guys!