CONTINUOUSWAVE

I recently purchased a 1998 17 Outrage II with a 130-HP Yamaha engine. I plan to add a stern mounted auxiliary engine of 8 to 10-HP.

The 17 OUTRAGE II has a swim platform on port so an auxiliary engine could only mount on the starboard side.

Give me suggestions on the best mount for [an 8 to 10-HP auxiliary engine].

Will 8-HP be enough power?

The boat weight is about 1750-lbs.

I am certain an 8-HP auxiliary engine will be completely sufficient for a 1998 17 OUTRAGE II boat. An 8-HP engine was used as an auxiliary engine on an OUTRAGE 22 and was completely sufficient. See the REFERENCE section article on that installation:

Mounting a Yamaha T8 Four-Stroke Auxiliary
On a 1992 OUTRAGE 22 with Evinrude 225-HP Main Engine
http://continuouswave.com/whaler/refere ... icker.html

I expect that even a 6-HP auxiliary would be sufficient for a 17-foot boat.

Without a transom to mount the auxiliary engine, you may have to fabricate or buy an engine mounting bracket. You should research the location of embedded wood reinforcement in the transom to be certain the auxiliary engine mount will be fastened to a reinforced area.

For examples of auxiliary engine installation that did not use a transom mount, see two articles in REFERENCE:

Auxiliary Engine Bracket for 15-foot Boston Whaler Boats
http://continuouswave.com/whaler/refere ... Motor.html

and

170 MONTAUK: Auxiliary Motor Installation Directly To Transom
http://continuouswave.com/whaler/refere ... liary.html

Before undertaking this project, I recommend you test the effect of the addition of a mounting bracket and another outboard engine hanging on the stern of the boat on the boat's static trim. The 17 OUTRAGE II is somewhat known for having limited freeboard at the stern. Adding another engine and a bracket could have a detrimental effect on the boat trim. You should simulate the added weight by adding at least the same weight inside the boat at the transom, and perhaps even more than the anticipated engine and bracket weight because the actual engine and bracket will be located aft of the transom. You may find that the effect of the added weight is not particularly favorable.

For comments about limited freeboard on the 17 OUTRAGE II boat see

1991 Outrage 17 Stern Waterline
viewtopic.php?f=7&t=2320

and

1994 Outrage 19'- High waterline
viewtopic.php?f=4&t=5762&p=33602

A good indicator of the suitability of the stern weight for the boat is to observe the relationship between the transom drains and the waterline at static trim. If the drain outlets are already at or below the waterline, adding weight to the stern will only tend to immerse the drains deeper and reduce freeboard at the stern.

The boat in question, a 1998 Outrage 17 II is a different design than the 1990-1995 Outrage 17 I and does not have the stern weight sensitivity.

1996-1999 Outrage 17 II:


1990-1995 Outrage 17 I: