Moving sterndrives

[Boat1]

I'd like to clarify some of my comments. First in regard to coulper failure that is not a correct word choice, the transmission tailstock would be under alot of stress, (assuming a plug-in style). With a plug in style, the rear mount would also be attached to the inner transom assembly, another stress point. If you are using a driveline I would try and maintain less than 5 degrees offset in the mating flanges. I have found more than this creates harmonics in the drive line that ultimately will load and unload the gears, beating the engagement surface of the gears and causing wear. As for drive height I think your proposed height will work just fine for a pleasure application, you would want the cavitation plate out of the water while on plane. I understand the references to the large boat/engine combinations, I agree the engines could move around some and not have an impact. This application, in my opinion, is very close coupled and even slight movement will have an effect on engine alignment, this alignment is critical to drive reliability. Possibly a rigid urethane insert style mount, if available, might be a good choice to reduce vibration and retain stability. Finally, I'm trying tp help with my comments, if they are not helpful I appologize for wasting everyone's time.

[larby]

Boat1, I see what you're getting at and you're absolutely right as far as I know, but I don't know if you're seeing what we're suggesting here. The standard rubber 'isolation' type mounts barely allow much movement, in the same manner as engine mounts in a car, or anything else for that matter. I get the impression you think we're suggesting the use of soft mounts that allow a noticable amount of movement, therefore allowing the engine to move out of tolerance causing an alignment issue?

James

[DAREDEVIL]

Originally Posted by Boat1

I'd like to clarify some of my comments. First in regard to coulper failure that is not a correct word choice, the transmission tailstock would be under alot of stress, (assuming a plug-in style). With a plug in style, the rear mount would also be attached to the inner transom assembly, another stress point. If you are using a driveline I would try and maintain less than 5 degrees offset in the mating flanges. I have found more than this creates harmonics in the drive line that ultimately will load and unload the gears, beating the engagement surface of the gears and causing wear. As for drive height I think your proposed height will work just fine for a pleasure application, you would want the cavitation plate out of the water while on plane. I understand the references to the large boat/engine combinations, I agree the engines could move around some and not have an impact. This application, in my opinion, is very close coupled and even slight movement will have an effect on engine alignment, this alignment is critical to drive reliability. Possibly a rigid urethane insert style mount, if available, might be a good choice to reduce vibration and retain stability. Finally, I'm trying tp help with my comments, if they are not helpful I appologize for wasting everyone's time.

Hello Boat 1, you will find that most of these guys know everything and realy can't be helped..LARBY is one of them..he has realy no clue about engines or boats ..but tells everybody what to do. I have still yet to see his boat running that he is trying to get going woth hios blower engine. Its funny that most of them on here bash me for actually speaking my mind and telling the truth.
But i like your explination and i 100% agree with you. The only thing those so called bushings do ..or are ment to do is keeping the vibration from the engine off the boat..not the other way around.....but larby thinks its for the saftey of the engine..lol
Its for not getting stress from the engine on the structure of the boat!!

LATER, now ya all have fun again..

[larby]

Go f*ck yourself

[MikeOakley]

Originally Posted by larby

Go f*ck yourself

+1
I´m sure there´s plenty who´s said it IRL too...

PS DD , Larbys 26 Puma cat will eat your boat in any condition, even with a single engine...

[DAREDEVIL]

Well, i kind of like how little you know.. my boat is a single engine aswell...and i love Larby's signature line...

Wonder why non of you actually understand it tho ??!!!

[OFFSHORE GINGER]

Originally Posted by larby

Go f*ck yourself

My, My, ha ha ha , and here i thought all of you guys on that side of the world were gentleman , ha ha ha ha

[wiggy808]

Not sure it was an unprovoked attack!

[Boat1]

Before custom making a cradle I would investigate how Yanmar handles the mounts for their Bravo drive application, they clearly have done all this before. Is this boat going to use a driveline or plug-in style transmission?

[Paul E]

Originally Posted by DAREDEVIL

Well, i kind of like how little you know.. my boat is a single engine aswell...and i love Larby's signature line...

Wonder why non of you actually understand it tho ??!!!

You said the engines will fit straight in, so I don't know why you're even posting in here still

[jw.]

Just a wee thought for you... in a twin engined application, can you suggest a situation where the forces on the engines will be in opposing directions to cause their spacing to decrease?

[larby]

That did actually cross my mind, but I figured there is going to be an occasion eventually when that happens due to a purely downward force, or a combination of a side force and heavy throttling. I saw a vid a while ago of a twin rigged boat who's engine hatch came off. Even though I can only imagine the engines were solid mounted, I was shocked at how much the engines moved about, independantly as well as in unison.

James

[DAREDEVIL]

Originally Posted by Paul E

You said the engines will fit straight in, so I don't know why you're even posting in here still

i still say they do !

did you guys actually ever hear that the more cooks are in the kitchen the worst is the taste ???

Just sayin, FIND 1 person that knows how to really rig a boat and let him do it all and figure it out !!! ( YOUR BEST BET )

[larby]

Originally Posted by DAREDEVIL

i still say they do !

did you guys actually ever hear that the more cooks are in the kitchen the worst is the taste ???

Just sayin, FIND 1 person that knows how to really rig a boat and let him do it all and figure it out !!! ( YOUR BEST BET )

So why did you feel a need to get involved then? We were doing far better without you.

[DAREDEVIL]

Originally Posted by larby

So why did you feel a need to get involved then? We were doing far better without you.

Go buy your carbs and get your freakn engine running before you give advise and have no clue !!

[larby]

Ok, well you obviously didn't get the point when I told you to go do one, so answer me this... Where have I given advice in this thread that was wrong?

Just because my current boat isn't finished (due to time, not lack of ability), doesn't mean I don't know what I'm talking about. Nor, for that matter have I suggested I do know everything, or much at all about mounting twins having never done it before, I'm just trying to help a like minded friend with his problem. I wasn't going to get involved but no-one else did so I made a suggestion. Something you'd find if you read back to the beginning.

So, tell me where I'm going wrong, or go try to kiss a moving train.

James

[jw.]

Would you children please go stand in the corners until you can be civil to each other?

[Paul E]

Originally Posted by DAREDEVIL

Go buy your carbs and get your freakn engine running before you give advise and have no clue !!

So because Larby asked for advice from people in the know about carb/blower set-ups, that means he knows nothing about anything else?

It's no wonder everyone thinks you're an asshole despite you just claiming to be 'different'

Peter's in the same place Larby was a few years back, diving in at the deep end, wanting to learn and DIY it, and trying to get advice from helpful people in the know. Trust me, I've seen his Revenger, and he's taken all the advice and guidance (some bad, some good) and done a superb job. For what it's worth I'm not completely clueless as my dad's been a boatbuilder for 2/3rds of his 64 years and has forgotten more than what most people in the industry ever knew in the first place. I've seen a lot of shoddy workmanship and crappy builds that he's had to put right, and there's a reason he warned me off buying an American boat!

Peter doesn't deserve the crap on this thread, and he doesn't deserve crappy know it all answers from people that have only seen half the information either.

Cut Larby some slack, and stop pretending like you know absolutely everything when you quite clearly don't. You might not agree with what he's suggesting, that's up to you, but he's never once suggested that it's the only way of doing it, it's all been sensible, useful discussion.

A mod should clean this up

[Jon Holmes]

I think most people on here think Larby is alright. Where as the results of DD's Mullet Poll speak for themselves.

[larby]

Thanks for the support guys. Some people probably think I talk too much/am too opinionated or whatever, but I'm just trying to help people as much as I can. It's not that long since I knew nothing and came on here to ask all sorts of silly questions!!

James