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Author Topic:   Engine Mounting Height Guideline

L H G posted 11-11-2008 06:17 PM ET (US)
Found this link that has some valuable information. The engine mounting height guildelines are of particular interest, which indiacates that if your boat won't go over 45 MPH, raising the engine is a waste of time.
jimh posted 11-11-2008 08:38 PM ET (US)
That link gives you some of the same information (such as "engine mounting height guidelines... of particular interest") as our REFERENCE section has for a long time:
http://continuouswave.com/whaler/reference/engineMountingHeight.html
number9 posted 11-12-2008 04:55 AM ET (US)
Jim,
Think the link is rather good and does provide some some additional info not on this one, unless it has been missed by me. Might want to think about incorporating some of it.
Bill
jimh posted 11-12-2008 09:35 AM ET (US)
Bill--There are great resources on the web, but we don't try to collect lists of them. We leave that to Google.
jimh posted 11-12-2008 09:40 AM ET (US)
For information on engine mounting guidelines, see the FAQ:
Q8: How Does the Engine Mount to the Transom?
http://continuouswave.com/whaler/reference/FAQ/#Q8
Q9: What is the Standard Transom Hole Layout?
http://continuouswave.com/whaler/reference/FAQ/#Q9
For Mercury's recommendation on engine mounting height, see
Engine Mounting Height
Guidelines for outboard transom mounted engines
http://continuouswave.com/whaler/reference/engineMountingHeight.html
Tohsgib posted 11-12-2008 12:10 PM ET (US)
I know from experience that moving a 90hp up 2 holes on a Newport gave me almost 2mph...how can 20 minutes to gain 2mph be a waste of time? Also that is almost 2" less draft.
Tom W Clark posted 11-12-2008 12:13 PM ET (US)
1-1/2" less draft. Bolt hole spacing on all outboards is 3/4".
Tohsgib posted 11-12-2008 01:16 PM ET (US)
I said almost 2"
Tom W Clark posted 11-12-2008 02:04 PM ET (US)
That is perfectly true. Nothing I said disagrees with that ;-)
Tohsgib posted 11-12-2008 02:11 PM ET (US)
I know ;)
number9 posted 11-16-2008 02:19 AM ET (US)
I appreciate the link's illustrations to help understand water flow, particularly to the water pump intakes.
Recently purchased a couple of recent Mercury OB Service Manual and must say I'm very impressed. They even include some Theory of Operation sections. Sure is nice to know what and why it's happening on a computer controlled EFI engine.
Hope they keep the good work.
L H G posted 11-16-2008 02:23 PM ET (US)
That link is just one page from Mercury's Rigging Technical Manual. If you think that is good, you should see the whole telephone sized book!
number9 posted 11-16-2008 05:04 PM ET (US)
L H G,
I can certainly imagine, will have to keep my eyes open for one.
BWhalerlover posted 11-17-2008 07:31 AM ET (US)
That's a good link and provides information not found in the reference section. The reference section is a good starting point for the study of engine height changes on performance. The supplied information from poster LHG continues it to the next level in my opinion.
jimh posted 11-18-2008 12:35 AM ET (US)
Outboard manufacturers publish rigging guides for their motors. If you want to read one, order it from your dealer. That's the next level. I've read the Bombardier rigging guide, and it is amazingly comprehensive. It's a good investment for anyone planning on installing their own motor.
However, you don't need it to figure out your engine mounting height. Or where to drill the holes in the transom.
BWhalerlover posted 11-19-2008 07:08 AM ET (US)
Jimh,
Why the xenophobia towards contributions to the site from others "in the know"? You have a great website and a dandy reference section as well. Life is not static and learning should not be either. We can all learn a bit more about engine mounting heights and its affect on the boat. Over the years, all manufacturers have produced both good and not-so-good factory rigging instructions. I agree that the Bombardier rigging instructions that came with my E-tec are great but that does not mean that I close my mind to any other source.

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Author	Topic: Engine Mounting Height Guideline
L H G	posted 11-11-2008 06:17 PM ET (US) Found this link that has some valuable information. The engine mounting height guildelines are of particular interest, which indiacates that if your boat won't go over 45 MPH, raising the engine is a waste of time.
jimh	posted 11-11-2008 08:38 PM ET (US) That link gives you some of the same information (such as "engine mounting height guidelines... of particular interest") as our REFERENCE section has for a long time: http://continuouswave.com/whaler/reference/engineMountingHeight.html
number9	posted 11-12-2008 04:55 AM ET (US) Jim, Think the link is rather good and does provide some some additional info not on this one, unless it has been missed by me. Might want to think about incorporating some of it. Bill
jimh	posted 11-12-2008 09:35 AM ET (US) Bill--There are great resources on the web, but we don't try to collect lists of them. We leave that to Google.
jimh	posted 11-12-2008 09:40 AM ET (US) For information on engine mounting guidelines, see the FAQ: Q8: How Does the Engine Mount to the Transom? http://continuouswave.com/whaler/reference/FAQ/#Q8 Q9: What is the Standard Transom Hole Layout? http://continuouswave.com/whaler/reference/FAQ/#Q9 For Mercury's recommendation on engine mounting height, see Engine Mounting Height Guidelines for outboard transom mounted engines http://continuouswave.com/whaler/reference/engineMountingHeight.html
Tohsgib	posted 11-12-2008 12:10 PM ET (US) I know from experience that moving a 90hp up 2 holes on a Newport gave me almost 2mph...how can 20 minutes to gain 2mph be a waste of time? Also that is almost 2" less draft.
Tom W Clark	posted 11-12-2008 12:13 PM ET (US) 1-1/2" less draft. Bolt hole spacing on all outboards is 3/4".
Tohsgib	posted 11-12-2008 01:16 PM ET (US) I said almost 2"
Tom W Clark	posted 11-12-2008 02:04 PM ET (US) That is perfectly true. Nothing I said disagrees with that ;-)
Tohsgib	posted 11-12-2008 02:11 PM ET (US) I know ;)
number9	posted 11-16-2008 02:19 AM ET (US) I appreciate the link's illustrations to help understand water flow, particularly to the water pump intakes. Recently purchased a couple of recent Mercury OB Service Manual and must say I'm very impressed. They even include some Theory of Operation sections. Sure is nice to know what and why it's happening on a computer controlled EFI engine. Hope they keep the good work.
L H G	posted 11-16-2008 02:23 PM ET (US) That link is just one page from Mercury's Rigging Technical Manual. If you think that is good, you should see the whole telephone sized book!
number9	posted 11-16-2008 05:04 PM ET (US) L H G, I can certainly imagine, will have to keep my eyes open for one.
BWhalerlover	posted 11-17-2008 07:31 AM ET (US) That's a good link and provides information not found in the reference section. The reference section is a good starting point for the study of engine height changes on performance. The supplied information from poster LHG continues it to the next level in my opinion.
jimh	posted 11-18-2008 12:35 AM ET (US) Outboard manufacturers publish rigging guides for their motors. If you want to read one, order it from your dealer. That's the next level. I've read the Bombardier rigging guide, and it is amazingly comprehensive. It's a good investment for anyone planning on installing their own motor. However, you don't need it to figure out your engine mounting height. Or where to drill the holes in the transom.
BWhalerlover	posted 11-19-2008 07:08 AM ET (US) Jimh, Why the xenophobia towards contributions to the site from others "in the know"? You have a great website and a dandy reference section as well. Life is not static and learning should not be either. We can all learn a bit more about engine mounting heights and its affect on the boat. Over the years, all manufacturers have produced both good and not-so-good factory rigging instructions. I agree that the Bombardier rigging instructions that came with my E-tec are great but that does not mean that I close my mind to any other source.