Volvo engines (For Crazyhorse) - Page 8

crazyhorse · 03 March 2003, 20:10

Fair comment DD it will be an interesting read Im sure.

What you doing with that Sib.have you bought another rib yet?

crazyhorse · 04 March 2003, 22:36

Is this JF engine?Or one that maybe Dirk tuned a bit back?

Dirk Diggler · 04 March 2003, 22:48

I see you have been lurking round the MBY forum, you closet hardboater!

crazyhorse · 04 March 2003, 23:42

It just reminded me of your Engines when I saw it.

crazyhorse · 08 March 2003, 00:10

So where you been JW,and what you been up to in that garage of yours?

jwalker · 08 March 2003, 00:31

I'm doin' ok. Been building the trailer. I got held back a couple of weeks ago so it's taken a while. However, just finishing some of the fiddly bits - mountings for mudguards, rollers etc. It'll be complete this weekend and off for galvanising when it can be collected. The boat will have the DPX mounted during the week. I've been looking into moving the engine forward about 1.5mtrs. Partly to better balance the boat but it also may provide a few other benefits. There'll be a large seating area at the back which could be arranged in various ways. No decisions yet. It also means that only one large hole need be cut through the deck. The 2 tanks can go in and be pushed forward and the third can be pushed back. It'll leave access, in the engine compartment, to all their connections and the pumping system. The engine housing can be better vented to prevent water ingress. If I build the engine housing with a flat top it will make a good table or a place to strap the wee inflatable etc. Improved access to the wing engine and the sterndrive. Lots of good reasons. Help my brain out and give me all the reasons that it's not such a good idea.
How about yourself? Your new boat looks the business. It'll be heavy with all that gear but I can imagine being anchored in a sheltered bay in the Outer Islands with deep blue water below one, a glass of Macallan in the hand, feet kicked up onto the tubes and the red sun just dipping down to the horizon.

Oh gawd, I'm off to me bed so's I can continue dreaming.
Night night.
JW.

crazyhorse · 08 March 2003, 00:39

She aint that Heavy as she is alli, but you got it in one as far as the deep blue outer Islands.

I will have a look at your post tommorow and have a think and email you any ideas. It sure sound interesting.

I think we can share that dream.

Jonny Fuller · 08 March 2003, 07:14

Quote:

Originally posted by jwalker
The boat will have the DPX mounted during the week. I've been looking into moving the engine forward about 1.5mtrs. Partly to better balance the boat but it also may provide a few other benefits. JW.

JW,

Do you mean like this,

Jonny Fuller · 08 March 2003, 07:15

Or this

crazyhorse · 08 March 2003, 10:55

Nice pics JF,Will you pop over to Genoa show and get some more for us?

How is the exhaust problems ,are they now sorted?

Jonny Fuller · 08 March 2003, 11:54

Quote:

Originally posted by crazyhorse
Nice pics JF,Will you pop over to Genoa show and get some more for us?

Not Genoa, Miami

jwalker · 08 March 2003, 20:31

Yes Jon, very much like that but with a bigger separation. It should be a bit simpler in that the engine only has one exhaust.
JW.

crazyhorse · 08 March 2003, 21:07

Well JW its a realy big job, that your doing to your boat.

Infact I dont think there is anything bigger than moveing your inboard engine position.

So good luck

jwalker · 08 March 2003, 21:47

Hi CH. Well I'm not really moving it because it's not fitted. The deck is still intact. The boat balance is always an issue depending on sea conditions. The engine at the stern will give the best speed and speed is nice but I've been on many a journey where I would have given money for some weight further forward. Head seas with a wind whipped chop of about 4-5-6ft and wave length just wrong for the hull length. 10knots max for hours on end to be safe. Whew, I can still feel the waves now. 'Look out here's another one bursting over the bow!' Know what I mean?
The 3 tanks is a fuel reliability issue (Burst one and there are still two left.) and also an method of altering boat trim. Provided they're not all full of course.
The only thing that concerns me slightly is that, on landing badly, the boat can end up being supported at both ends and the weight of the engine will tend to bend it at the hole in the deck where the engine lives. The engine bearers can be made chunkier to help strengthen the hull and this may be more than enough.
There's plenty of food for thought yet.

Comments from anyone who really knows about this type of thing will be greatly received.

Got waylaid today so didn't finish the trailer as hoped. It'll be done by mid week. With no more interuptions, the DPX X height should be calculated during the week and there will be a big hole in the transom next weekend.
JW.

crazyhorse · 08 March 2003, 21:59

JW speak to a naval architect and get a weight table from the designer of the Hull, Before even contemplating what your doing.

Thats my advice and it may not be what you want to hear but its such a complicated job,that its better to get it right now or pay the price later.

You may already know enough about the stability and weight table but if you dont then dont go near the boat till you do,as you could right a good boat off.

Good luck

crazyhorse · 08 March 2003, 22:53

Well I learnt I want a 4 inch fuel inlet and pipe today,So there is a tip.

Anybody got any info on a cheap Air Con system and no silly answeres like get a open rib, or cut the roof off,you know the sort of thing I mean Dirk/JF

Jonny Fuller · 09 March 2003, 10:33

JW,
you are bang on, getting that motor in the right place for your intended use is critical, and CH, I dissagree, moving the motor isn't that big a deal, especially if there isn't currently one in there!
Maintaining pitch stability in the lumpy stuff is all about two things, centre of gravity (for & aft) and how warped your deadrise is, simple as that! Trouble is, it's all a trade off, as always!
Like you said, weight well aft, constant deadrise, plenty of power, you've got the basis of a raceboat, great when driving like your life depends on it (this is my boat all over)
But, if you want a good ride at moderate speed in shitty conditions you need the opposite, weight amidships, plenty of warp (deadrise increasing toward the bow), plenty of power is still handy, maybe even a bow ballast tank like we use in racing, as this is much more efficient than trim tabs/drive
Now you've got a near wave piercer (Scorpion 9.5)
Bill Malloney designed a range of runabouts and cruisers in the 70's called "sorcerers" these boats had stacks of warp and the larger ones (biggest was I think 25') competed in the Cowes-Torquay a few times with great success against much bigger, more powerfull boats when the conditions were nasty.
Mr Mallony is a clever old bugger,aeronautical design background, no guessing with his designs! and there is a possibility of a rib being made from a 31 hull of his. I think this would be very interesting for you go-anywhere boys!

P.S. The down side of the boat that was good in the rough is, if you try to go fast, by that I mean FAST, it will swop ends(hook) given the first chance, very nasty! plus it won't be that quick, top end as the wetted area will be high.

crazyhorse · 09 March 2003, 10:55

JF what you're forgetting here, is this hull is a Humber 8.5 and it was designed at some point to take x engine and it is a good sea boat as it is,If you start putting weights like engines and tanks in different positions then you need be very accurate with the positions as the original hull has a weight table that was the designers brief and that was his optimum level of ballance and performance,any changes to that concept are a big gamble,hopefully in this case it will work out,But it is less of a gamble if you get a naval architect to check what your doing.

I would not even contemplate withought a proffesional look at it first and giving me the thumbs up.

But I think JW will do what he believes is right and follow your lead,So good luck.

Dirk Diggler · 09 March 2003, 11:05

I'm probably going to regret asking this, but why do you need a 4" fuel inlet?

Jonny Fuller · 09 March 2003, 11:12

Quote:

Originally posted by crazyhorse
JF as the original hull has a weight table that was the designers brief and that was his optimum level of ballance and performance

You're being very presumptious, the truth is, very few boats in this category start as any more than a drawing on a fag packet by a person who has a feel for the job!
With respect, you do have a bit of an obsession with forms, paperwork and rules, in the real world, these are often created AFTER the boat, just to satisfy the rules and regs!
Having a bit of paper that says you can go out in a 12, writen by a tosser in europe, is of little comfort when your boat has cracked and you are sinking in an 8!(or your tube has fallen off and someone has left a load of holes behind it to ensure quick flooding)LOL