Volvo engines (For Crazyhorse) - Page 12

crazyhorse · 10 March 2003, 10:26

Jf you are guessing on the outcome of your proposed friends rib success,as the market will decide weather it is any good or not. I agree that you need experiance/proffesional on a job like this or be very lucky or both.

You seem to not be happy about qualified Naval Architects or paper pushers,That is your perogative but some of us need them for advice as we may not be aware of who is good or indeed who is bad.So we employ what we think is the best,you cant knock all people who have qualifications in the same way you cant knock all those people that dont but have beneficial experience.

You pick your team and have faith in them in the hope they get it right,or you do it yourself if you feel confident in your work/experiance.

The outcome will be what you end up with.

Not haveing the benefit of your experience I work with consultants/proffesionals to get what I want and otheres that I believe know there onions.

So far they got it right imho,but it is to soon to say long term.

Jonny Fuller · 10 March 2003, 10:38

OKI-DOKI

jwalker · 10 March 2003, 10:45

Hi CH,
I can say you have in my oppinion no alternative than to move the engine forward or the nose will be in the air with just the two of you.

Yep, that's what I said.

How did I know?

Spooky isn't it.

Competent DIYers who get it wrong eh - maybe they're not so competent.

JW.

crazyhorse · 10 March 2003, 10:47

Good luck with it JW

Jonny Fuller · 10 March 2003, 10:59

JW, so does this mean we can now get on with this jack shaft?
I'm familiar with the Mercruiser jack shaft as it's used quite a bit for staggered installations, it's quite a simple setup, a tailstock is installed on the inner transom assy which recieves the donkeys dick(splined shaft from leg) this then has a 4" flange, automotive propshaft stylee to link your prop shaft to the motor, it's pretty simple!
However, as the vilevo has it's bearings to support the UJ'd shaft(equivalent to donkeys dick) within the bell housing I'm not sure how they do it, clearly it must have some sort of tailstock, but as the volvo doesn't have any location other than a big hole with huge "O" rings, I don't know how they would stop the tailstock from trying to spin, maybe it's a different inner transom assy!
Anyway, sounds like you have enough "gut instinct" to deal with it!

Good luck.

jwalker · 10 March 2003, 12:10

Volvo supply a kit. Transom end is a housing with a couple of taper roller bearings which locates onto the splined outdrive shaft. The housing is attached to the transom to tether it. In the drawings is appears that the fixing is a bit flexible. The other end is a bellhousing with a drive which, again from the drawings, appears to be rubber. A bit like a very large CV joint but with rubber instead of the balls. The two are linked by a normal propshaft or a shaft with CV's. If the installation is nearly straight, there will be no need for the CV system because the velocity in will equal the velocity out - normal UJ's will be fine.

We're making light of this DIY thing but there's more to it than gut feeling. If you have a good wealth of knowledge, you use your experience and apply principles in a considered way. With the engine thing it was fairly easy to estimate. The weight of water displaced = the weight of the motor so it was not difficult to measure the hull at the approx engine point and estimate the amount the boat would sink. Taking moments about the CG for the tanks and consul etc. gives a fair astimate of what is likely to be the outcome. Plus, I've now got CH's permission!

It isn't necessarily going to happen because there are all sorts of alternatives to the layout of the boat. It's likely, but not yet a conclusion. I'm still sorting the braking system for the trailer. Throwing away all the crappy cables etc. and inventing an alternative. When that is finished, I'll put my mind fully to the boat, produce some drawings of alternatives and come up with the final solution.
JW.

Jonny Fuller · 10 March 2003, 12:24

In the states now, you can buy real nice SS discs and callipers, hydraulic has to be the way to go, although I think untill recently they were illegal in the UK, now legal I believe, but not easy to have parping brake which is required by law, maybe you could use discs and callipers, some over here on cars (jag I think) have an extra bit with a set of mechanically operated pads just for the handbrake! or b******s to the regs and buy a wheel chock or two! that's what the Yanks do

jwalker · 10 March 2003, 13:14

Jon
My last trailer had hydraulic brakes and after I modfied them with brass pistons they have worked very well. However, they are not legal because the law states that the brake must be auto reversing. Type approval is also a problem. I've bought suspension units with brakes so I'm going to address their short commings for this one.
Manos mentioned SS discs in one of his posts. I'm a little sceptical, knowing the very poor heat conduction of SS, because I can envisage them warping each time the brakes are applied in anger. Also, SS rusts badly when wet in the absence of air. This is likely to be the case at the pad/disc when the trailer is parked for a length of time. However, I'm happy to be put right on this.
Thanks for the info though. Any brochers etc?
JW.

Jonny Fuller · 10 March 2003, 13:31

JW, try this one, http://www.boat-trailers.com/brakes.htm
Or this, http://www.championtrailers.com/TIED...BRAKE_KITS.HTM
or these,
http://www.fastloadtrailers.com/discBrakes.JPG

Regards

Jonny Fuller · 10 March 2003, 13:48

Quote:

Originally posted by crazyhorse
JW,Ok having slept on your problem about where to put the engine/tanks,I can confirm that in my humble oppinion that given the Hull weighs aproximatly 1 ton and the engine weighs over half a ton and we floated a 30 ft rib that was down by the stern with a Kad300 in her in Autoship and she was realy low at the back end,in fact the water was 4 inches up the tubes.I can say you have in my oppinion no alternative than to move the engine forward or the nose will be in the air with just the two of you. I am no stability expert,and have advised of one I personaly can recommend .IMHO

I promise I'm not raking this up again, but just been looking back through the thread and it struck me that most of your comments, particulaly with respect to the RCD (Really Crappy Document) refer to C of G vers's boyancy in a static situation, freeboard an all that tosh, whilst important when stationary (not I hope when your kad300 gives up) it has very little relevance when underway, when underway the dynamic lift generated by your hull, which of course will move aft as your speed increases is gonna dictate how level ya rubber dub runs, thats the whole bag with this warped deadrise thing! as a good example, my old hardy looks like it's about to sink at rest, but underway it's level!

anyway, just had to mention it, sorry.

crazyhorse · 10 March 2003, 14:35

If you say so

Jonny Fuller · 10 March 2003, 14:41

Quote:

Originally posted by crazyhorse
If you say so

Do I detect a hint of sarcasm?

Alan Priddy · 10 March 2003, 16:06

For what it is worth, if you move your engine forward on this installation you will end up with a bloody wet boat!
It will Ok when you are up on the plane and running fast but as soon as you have to start driving the boat in big seas the centre of lift / gravity will be all wrong. Off course it may be a case of you know something that some of the very best builders do not, in which case I will say sorry for my comments. But not untill I have seen the boat perform. If you do not like your nose in the air you can always fit large trim tabs!! Alan P

jwalker · 10 March 2003, 16:24

Do I detect a hint of sarcasm too?

JW.

But, all comment greatfully accepted.

Dirk Diggler · 10 March 2003, 16:38

A herd of cows, a pride of lions, a ????? of boat designers?

Manos · 10 March 2003, 16:56

...and who's got the BSc (Hons), MSc and the PHd DD??

Dirk Diggler · 10 March 2003, 17:03

Quote:

Originally posted by Manos
...and who's got the BSc (Hons), MSc and the PHd DD??

Macdonalds school of hamburgerology?

jwalker · 10 March 2003, 17:16

Now DD, don't you start winding folk up. Again.

Alan P, elaborage on your previous post please. Reasons why.

JW.

Alan Priddy · 10 March 2003, 17:33

The drive is at the rear of the boat and the weight would be nearly in the middle. Understand I am talking about using the boat in difficult seas. The waves will be rolloing underneath the tubes (hopefully) causing the stern of the boat to lift as they roll by. You have 1/2 tonne of metal amidships and you need to use the power to stop the bow of the boat going under water, You might get away with it in a petrol boat but the time delay between the"Lag" of the turbo and the wave will never be right. Have a look at some of the older styled commercial boats, Delta, Halmatic etc and you will see that all of these boats were designed by reputable people who now only fit engines in the back of boats. If you want to build a good deep sea boat stick a pair of big outboards on the back and drive it like a Dirt Bike Alan P

jwalker · 10 March 2003, 17:49

That's better, reasoned comment. Yes, it had occured to me. It's in the reasons not to do it list. One other thing I had against is the angle of attack of the spray rails. If they're a bit bow down the drive will need to be trimmed right out to lift the bow just for normal running.

Keep 'em comming.

JW.