Go with the biggest, 9.9 hp. On a windy day you will need all of that
on a 3,000 lb boat. You could probably get by with 6 hp in smooth
conditions buy it will not be enough to get through waves properly
when the wind is blowing hard. You should also get a special prop
with a lower pitch ratio than normal, and as many blades as possible,
like a work boat prop.


On 16 May 2006 14:27:35 -0700, "
wrote:

I would like to add an auxiliary outboard motor to my heavy 18-ft
fiberglass boat. I need it for (1) Backup "go home" power in case the
10-years old main motor dies (2) Trolling for fishes (3) Use it in
lakes that only allow no more than 9.9hp motor.

I would like to know how many horse power the auxiliary motor should
have. The boat is around 3000-lb (this includes everything like
people, fuel and cooler). It is 18-ft long and I figure that it has
16-ft at the water level. It is 12" draft. The hull is a semi-V. The
boat is a center console. I guess I am asking for a motor that can run
this boat right at the displacement speed (hull speed?).

Someone may say that bigger is better. But I cannot get more than
9.9hp motor because I need to use it in lakes that has
9.9hp-or-less-only limit. This sets the upper limit. I figure I
really don't need a large auxiliary motor because I will not run the
boat off shore (the boat is a "bay boat" and should not be used off
shore). And I will not run the boat when the weather is not good
because I am afraid of sea-sick.

I am hoping that I may be able to use something smaller than 9.9hp;
then I can save money on the motor and fuel. Moreover, I hope I can
use a small and light weight outboard motor that I can mount it in a
small row boat. If it is heavy, I probably will not be able to
dismount it at ease.

So, what I am asking a

- What is the displacement speed of my boat?
What horsepower of auxiliary outboard can run
my boat right at the displacement speed?

- What is the lowest limit (in term of horsepower) that
the auxiliary outboard should have without running the
risk of having the boat got stuck under normal wind and
current situation?

- What size do you recommend?

Thanks in advance for any info.

Jay Chan

Seem like the choice is between 9.9hp and 6hp. I don't want to run a
boat when I expect the wind will be blowing hard. In theory, this
means that a 6hp should be good enough. But I remember one time I ran
a boat and the day started quite well enough, and then in the afternoon
the wind started picking up. Sound like a 9.9hp is a better bet just
in case the weather unexpectedly changed right in the middle of a trip
in a 9.9hp-only lake. Now, I just need to find a way to dismount/mount
a 100-lb 9.9hp outboard by myself when I need to use the outboard in a
small row boat. Thanks for sharing the info.

Thanks for the info about prop with low pitch and many blades. Do I
need to change the prop back to the way it was when I move the outboard
to a small boat?

Jay Chan


Wayne.B wrote:
Go with the biggest, 9.9 hp. On a windy day you will need all of that
on a 3,000 lb boat. You could probably get by with 6 hp in smooth
conditions buy it will not be enough to get through waves properly
when the wind is blowing hard. You should also get a special prop
with a lower pitch ratio than normal, and as many blades as possible,
like a work boat prop.


On 16 May 2006 14:27:35 -0700, "
wrote:

I would like to add an auxiliary outboard motor to my heavy 18-ft
fiberglass boat. I need it for (1) Backup "go home" power in case the
10-years old main motor dies (2) Trolling for fishes (3) Use it in
lakes that only allow no more than 9.9hp motor.

I would like to know how many horse power the auxiliary motor should
have. The boat is around 3000-lb (this includes everything like
people, fuel and cooler). It is 18-ft long and I figure that it has
16-ft at the water level. It is 12" draft. The hull is a semi-V. The
boat is a center console. I guess I am asking for a motor that can run
this boat right at the displacement speed (hull speed?).

Someone may say that bigger is better. But I cannot get more than
9.9hp motor because I need to use it in lakes that has
9.9hp-or-less-only limit. This sets the upper limit. I figure I
really don't need a large auxiliary motor because I will not run the
boat off shore (the boat is a "bay boat" and should not be used off
shore). And I will not run the boat when the weather is not good
because I am afraid of sea-sick.

I am hoping that I may be able to use something smaller than 9.9hp;
then I can save money on the motor and fuel. Moreover, I hope I can
use a small and light weight outboard motor that I can mount it in a
small row boat. If it is heavy, I probably will not be able to
dismount it at ease.

So, what I am asking a

- What is the displacement speed of my boat?
What horsepower of auxiliary outboard can run
my boat right at the displacement speed?

- What is the lowest limit (in term of horsepower) that
the auxiliary outboard should have without running the
risk of having the boat got stuck under normal wind and
current situation?

- What size do you recommend?

Thanks in advance for any info.

Jay Chan

On 17 May 2006 08:10:51 -0700, "
wrote:

Now, I just need to find a way to dismount/mount
a 100-lb 9.9hp outboard by myself when I need to use the outboard in a
small row boat.

Try something like this:

http://www.yachtsofstuff.com/userPos...ff&cexs=ocmar3

You could probably build your own from steel channel.

Thanks for the info about prop with low pitch and many blades. Do I
need to change the prop back to the way it was when I move the outboard
to a small boat?

For optimal performance and motor longevity, the prop always should be
matched to the load. The risk of using a low pitch prop on a light
weight boat is over reving the engine and not making full boat speed.

Wayne.B wrote:
On 17 May 2006 08:10:51 -0700, "
wrote:

Now, I just need to find a way to dismount/mount
a 100-lb 9.9hp outboard by myself when I need to use the outboard in a
small row boat.

Try something like this:

http://www.yachtsofstuff.com/userPos...ff&cexs=ocmar3

You could probably build your own from steel channel.

Thanks for the info about prop with low pitch and many blades. Do I
need to change the prop back to the way it was when I move the outboard
to a small boat?

For optimal performance and motor longevity, the prop always should be
matched to the load. The risk of using a low pitch prop on a light
weight boat is over reving the engine and not making full boat speed.

Thanks for the link. Now I realize that I should be able to handle
100-lb motor without any problem. I didn't think this thoroughly.
Sorry about this. I think all I need is a mobile motor mount where I
can rest the motor on it while I move the motor from one boat to
another boat.

Also thanks for pointing out the need of matching the prop to the boat.

Jay Chan