The basics.

I've got a 1985 seaway V hull that weighs in around 2k. It is powered by
an OMC 1.6 L seadrive. Full throttle range is listed as 4500 to 5500 RPM
and has a 13 1/4 X 17 three bladed prop on it. The prop's condition is
such that it has to be replaced come spring. I will, at some point, have
the existing one repaired and use it for a spare.

I fish. I don't foresee towing or pulling anything, skiers, float toys,
etc, behind the boat. While high speed is nice my main interest is
efficiency. Especially in fuel consumption and range.

As it sits the boat runs about 30MPH at 5500 RPM and falls off the plane
right around 20 MPH at 4600RPM. These figures may, considering the
condition of the present prop, improve slightly with a new prop of the
same size. I don't know that for sure though.

Looking at the figures it appears to me that, though I would like to be
able to maintain the plane down to about 17 MPH, this is about as good
as it gets for the boat/engine combination.

Is it? Would I be able to realize something more efficient with a
different prop, and, more importantly for making my decision, What
effects be if I were to change to a four blade and or change the pitch,
maybe even change the size if that is possible? Stainless steel is not
an option. I fish the rocky coast around Boston harbor and would rather
replace a prop rather then the lower end should I get stupid.

PLEASE, just comments on the matter at hand and try not to end up in an
infantile name calling contest of no value.

Thank you





--
MikeG
Heirloom Woods
www.heirloom-woods.net

Mike,

I have a 1985 21 ft Sea Ray 210C (cuddy cabin) with the OMC drive. Although
the boat already had hydraulic trim tabs I found that I got a significant
improvement in lowering the planning speed by adding one of those trim fins
to the lower unit. It is much more effective at getting the bow down and the
boat on plane than anything else that I've tried. I would suggest that you
invest in one of these fins first. After you try it I'm sure that you will
just replace the prop without changing the pitch.

--
Charley


"MikeG" wrote in message
ews.com...

The basics.

I've got a 1985 seaway V hull that weighs in around 2k. It is powered by
an OMC 1.6 L seadrive. Full throttle range is listed as 4500 to 5500 RPM
and has a 13 1/4 X 17 three bladed prop on it. The prop's condition is
such that it has to be replaced come spring. I will, at some point, have
the existing one repaired and use it for a spare.

I fish. I don't foresee towing or pulling anything, skiers, float toys,
etc, behind the boat. While high speed is nice my main interest is
efficiency. Especially in fuel consumption and range.

As it sits the boat runs about 30MPH at 5500 RPM and falls off the plane
right around 20 MPH at 4600RPM. These figures may, considering the
condition of the present prop, improve slightly with a new prop of the
same size. I don't know that for sure though.

Looking at the figures it appears to me that, though I would like to be
able to maintain the plane down to about 17 MPH, this is about as good
as it gets for the boat/engine combination.

Is it? Would I be able to realize something more efficient with a
different prop, and, more importantly for making my decision, What
effects be if I were to change to a four blade and or change the pitch,
maybe even change the size if that is possible? Stainless steel is not
an option. I fish the rocky coast around Boston harbor and would rather
replace a prop rather then the lower end should I get stupid.

PLEASE, just comments on the matter at hand and try not to end up in an
infantile name calling contest of no value.

Thank you





--
MikeG
Heirloom Woods
www.heirloom-woods.net

Based on what you use the boat I would suggest the following:

1. Install whale tail. This will help maintain plane at lower speeds.
2. Increase pitch to a 19. This will get your rpms down, increase top
speed, and increase effeciency by traveling more distance per rpm. You
obviously dont want to go below 4500 on top end and the 19 will put you at
about 5200.
3. Going to a 4 blade is a matter of choice. It will cost more to purchase
and repair. It will help on the acceleration. And will probably help on
the planing speed but not as much as the whale tail. In this case - I would
probably stay w/ the 3 blade.

As for SS. There is a rubber hub that will break free long before you tear
up the gears in the outdrive if all that hits is the prop. Small strikes -
you will never know you did w/ the SS and the aluminum will have the ear
tore off.
SS will also give you a little better performance as the blade design is
more efficient.

Bottom line - Whale Tail and a SS 3 blade 19 pitch. You won't believe the
difference.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com
"MikeG" wrote in message
ews.com...

The basics.

I've got a 1985 seaway V hull that weighs in around 2k. It is powered by
an OMC 1.6 L seadrive. Full throttle range is listed as 4500 to 5500 RPM
and has a 13 1/4 X 17 three bladed prop on it. The prop's condition is
such that it has to be replaced come spring. I will, at some point, have
the existing one repaired and use it for a spare.

I fish. I don't foresee towing or pulling anything, skiers, float toys,
etc, behind the boat. While high speed is nice my main interest is
efficiency. Especially in fuel consumption and range.

As it sits the boat runs about 30MPH at 5500 RPM and falls off the plane
right around 20 MPH at 4600RPM. These figures may, considering the
condition of the present prop, improve slightly with a new prop of the
same size. I don't know that for sure though.

Looking at the figures it appears to me that, though I would like to be
able to maintain the plane down to about 17 MPH, this is about as good
as it gets for the boat/engine combination.

Is it? Would I be able to realize something more efficient with a
different prop, and, more importantly for making my decision, What
effects be if I were to change to a four blade and or change the pitch,
maybe even change the size if that is possible? Stainless steel is not
an option. I fish the rocky coast around Boston harbor and would rather
replace a prop rather then the lower end should I get stupid.

PLEASE, just comments on the matter at hand and try not to end up in an
infantile name calling contest of no value.

Thank you





--
MikeG
Heirloom Woods
www.heirloom-woods.net

First, I'd like to thank all the responders. You've touched on all the
points I've been pondering.

I think the general trend of the collective wisdom is that, with the
figures I supplied, I can possibly see some gains in efficiency but I am
pretty close to the boat/motor combination being at a point where gains
won't be significant.

Rather then try to reply to each post individually let me see if I can
cover them with this post.

Trim tabs - I'd dearly love them if only to get rid of the starboard
list when I am in the boat alone, which is most of the time. However if
afraid they won't make this years budget.

Four bladed prop - An idea I am playing with but, with the figures given
and keeping the same diameter and pitch, what will that do to top end
speed and RPM?

Lower planning speed - This is the tricky one for me so let me know
where I am going wrong. My boat has a planing hull as opposed to a
displacement hull. It is designed to work most efficiently up on a plane
rather then pushing the water out of the way al la displacement hull.
The
boat falls off the plane and starts pushing water below 20 MPH/4700 RPM.
A lower planing speed may mean it takes longer to get to a fishing spot
but if that means one or two more trips a month in the gas budget I can
live with it. So, and this is where I can see I may be looking at things
wrong, a lower planing speed means lower RPM s with the boat still
operating efficiently, planning rather then displacing, and lower RPM's
mean better mileage.

Whale tail or similar - A budgetable item I have been playing with the
idea of. The things I've read on these additions have all been
advertisements giving glowing reports on them. However, life being what
it is, you can't pay Peter with out stealing from Paul. What is the down
side to be considered?

Thanks again all
Mike


--
MikeG
Heirloom Woods
www.heirloom-woods.net

On Mon, 20 Dec 2004 10:42:42 -0500, MikeG
wrote:

~~ snippage ~~

Lower planning speed - This is the tricky one for me so let me know
where I am going wrong. My boat has a planing hull as opposed to a
displacement hull. It is designed to work most efficiently up on a plane
rather then pushing the water out of the way al la displacement hull.
The
boat falls off the plane and starts pushing water below 20 MPH/4700 RPM.
A lower planing speed may mean it takes longer to get to a fishing spot
but if that means one or two more trips a month in the gas budget I can
live with it. So, and this is where I can see I may be looking at things
wrong, a lower planing speed means lower RPM s with the boat still
operating efficiently, planning rather then displacing, and lower RPM's
mean better mileage.

I think you are way over estimating the difference 3 mph will make on
fuel consumption. Even after several long runs, I doubt if you are
going to save a significant amount of fuel savings such that you will
be able to make additional trips to the fishing grounds. What's the
difference between 17 and 20 in terms of RPM - a 5/600 at the most?
Not enough to justify tinkering with planing speeds.

My Ranger is 20 foot, has a FICHT (which I admit is probably more
efficient than EFI or a carbureted engine), but still, the difference
between 1800 and 2300 is pretty insignificant. I don't have the
figures right at hand, but as I remember, the difference was in the
very low tenths in terms of GPH.

Now having said that, I normally run at 30 mph which is right under 4k
- there I can see savings over the max speed of 42/43 mph at 5500.
But again, the difference is in tenths - closer to a full GPH, but
still tenths.

I'll look for the data when I return from fishing this afternoon and
give you some examples.

Whale tail or similar - A budgetable item I have been playing with the
idea of. The things I've read on these additions have all been
advertisements giving glowing reports on them. However, life being what
it is, you can't pay Peter with out stealing from Paul. What is the down
side to be considered?

For my money, these things suck.

The main reason is that they work even when you don't want them to
work. And you lose the ability to close trim the motor at speed.

On my Princecraft with the Johnson 25, yeah - they make a difference
in a lightly loaded boat by keeping the bow down.

For your application, it wouldn't be something that I would consider.

Later,

Tom

I haven't been following this thread, but you can add SmartTabs for below
$200.00 ..maybe even below $150.00 depending on size ( buy the "scratch and
dent" specials directly from the manufacturer, Nauticus ).

I have them on two smaller boats. They DO keep you on plane longer and at
lower speeds and they DO get you up on plane faster. I surely didn't buy
them for cost (fuel) savings but rather to get up and out from the shallows.
The over-all effects of Trim Tabs ( any brand of trim tabs ) is so very
positive that I think every boatowner/manufacturer ought to consider adding
them. --
RichG manager, Carolina Skiff Owners Group on MSN
http://groups.msn.com/CarolinaSkiffOwners
..

On Mon, 20 Dec 2004 20:42:10 GMT, "RichG"
wrote:

I haven't been following this thread, but you can add SmartTabs for below
$200.00 ..maybe even below $150.00 depending on size ( buy the "scratch and
dent" specials directly from the manufacturer, Nauticus ).

I have them on two smaller boats. They DO keep you on plane longer and at
lower speeds and they DO get you up on plane faster. I surely didn't buy
them for cost (fuel) savings but rather to get up and out from the shallows.
The over-all effects of Trim Tabs ( any brand of trim tabs ) is so very
positive that I think every boatowner/manufacturer ought to consider adding
them. --
RichG manager, Carolina Skiff Owners Group on MSN
http://groups.msn.com/CarolinaSkiffOwners

I'm curious as to what kind of boat you have to make that claim.

On my Ranger, trim tabs would be useless because of the transom
design. On my Contender, I guarantee you that the trim tabs have
nothing to do with getting on or off plane faster or longer. Lateral
stability at speed yes - planing, no.

Trim tabs aren't the end all for planing problems which is why I asked
what kind of boat you have. They work for some, but not all.

I have a suspicion that Mike's might not be one of those.

Later,

Tom

continued on the Thread entitled "SmartTabs"

--
..

"Short Wave Sportfishing" wrote in message
...
On Mon, 20 Dec 2004 20:42:10 GMT, "RichG"
wrote:

I haven't been following this thread, but you can add SmartTabs for below
$200.00 ..maybe even below $150.00 depending on size ( buy the "scratch
and
dent" specials directly from the manufacturer, Nauticus ).

I have them on two smaller boats. They DO keep you on plane longer and at
lower speeds and they DO get you up on plane faster. I surely didn't buy
them for cost (fuel) savings but rather to get up and out from the
shallows.
The over-all effects of Trim Tabs ( any brand of trim tabs ) is so very
positive that I think every boatowner/manufacturer ought to consider
adding
them. --
RichG manager, Carolina Skiff Owners Group on MSN
http://groups.msn.com/CarolinaSkiffOwners

I'm curious as to what kind of boat you have to make that claim.

On my Ranger, trim tabs would be useless because of the transom
design. On my Contender, I guarantee you that the trim tabs have
nothing to do with getting on or off plane faster or longer. Lateral
stability at speed yes - planing, no.

Trim tabs aren't the end all for planing problems which is why I asked
what kind of boat you have. They work for some, but not all.

I have a suspicion that Mike's might not be one of those.

Later,

Tom