48 foot Cray boat

Gday Guys and Gals,

Hopefully an easy one for you - I have a Westcoaster 48 foot fishing boat 1978 and want to repower her. I also want to go up in the horses range. The problem being that I am not sure how much the drive shaft can take or whether it is possible to upsize the hole in the hull to take a bigger one. 

So the question is; has anyone done this to one of these? Or does anyone know someone who used to work for Westcoaster so I can get a feel for the structural integrity and what is up in the tube so I can work out if this is just a bad idea? What happens when you make one of these old hulls do 25 knots? I have heard they flop about on the keel a bit  - is this true? How much power would I need to make it go that quick?

Any thoughts are greatly appreciated.

regards

Ian

 

 

 

 


Posts: 5738

Date Joined: 18/01/12

glass?

Thu, 2016-09-29 16:07

 is it a glass one?

I have repowered a few in earlier days, the last one I skippered had about 450hp Volvo but wasnt real fast, maybe 12-14 knots.
If you want it in survey, you will need to get approval for shaft size and material.

Sometimes changing shaft from 316 to Comsteel is enough to get the extra horses in without having to change bearings, coupling etc

____________________________________________________________________________

 Give a man a mask, and he'll show you his true face...

 

 

The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.

 

Posts: 8

Date Joined: 20/12/11

 Yes it is glass over timber

Thu, 2016-09-29 16:51

 Yes it is glass over timber stringers. It has an 8v92 in it and does about 12-14 knots. 

Posts: 8

Date Joined: 20/12/11

 I don't need it in survey. 

Thu, 2016-09-29 16:52

 I don't need it in survey. 

ranmar850's picture

Posts: 2702

Date Joined: 12/08/12

Top speed or cruise?

Thu, 2016-09-29 17:50

 if you are looking for 25knots top, you'd need to be looking at 700Hp minimum. This of course will depend on the hull weight, fitout, etc. Glass boats tend to slow down as they soak up a bit, always quickest when they go back in after an off-season out of water, bearing in  mind you probably have a massive slab of hardwood for a keel. 

You say it only does 12-14 knots with an 8V92? What Hp rating? NA or turboed (or twin turboed?) if you have about 450Hp you should get about 14 knot cruise, as Rob says above.  What does it top out at with a clean bottom? Should be about 17 knots? What state is the prop in? My attitude to pleasure boat motors is that they never get many hours up in the course of the years, so you may as well run them hard, up to 200rpm under max, as you will never wear them out . 

As Rob also said, changing the shaft material from 316 ( if that is what is has) to a higher grade can up your rating on the same diameter, without having to go through the business of a different stern bearing, stuffer box, etc. But takng it all into account, it  won't be a cheap exercise. Even if you can source something suitable in the hgher HP range, that isn't already more than half-worn , for a reasonable price, you'd still be looking at getting new mounts, exhaust, various brackets and fittings, that can easily set you back 10 or 15 K, if it isn't a straight drop in.

I'd try running the old girl harder, if she still has life in her, and see if you can manage a 16 knot cruise..if it's spent a long time just puttering around, it will smoke and protest something shocking for a while, and then run better than ever. Jimmies don't like being nursed :-)

Posts: 8

Date Joined: 20/12/11

 Excellent thank you. I

Thu, 2016-09-29 18:26

 Excellent thank you. I appreciate the advice. I am told it is a 500 hp Detroit. It is twin turbo. Yeah having started to price her up it isn't going to be cheap. One of the things I don't like about the boat is the engine box on the deck. Some modern engines are much lower profile and I might be able to cut the box away all together. Or at least reduce it. The engine leaks oil as fast as you can tip it in, but it runs ok. Ideally I would like 22-25 knots cruise speed and yes I am happy with running hard as a recreational boat. My biggest concerns are the drive shaft size as it runs down through the keel and how she might handle if she did run at that break neck speed. 

Does anyone know what the part of the keel where the shaft comes through is made from? Is it laid up glass or jarrah? It looks like I could drill it out half an inch based on the meat to each side of the shaft. But I wouldn't want to mess with that if it were raw timber in there. 

 

 

Browndog's picture

Posts: 580

Date Joined: 10/04/12

8V92

Thu, 2016-09-29 18:22

As a former Detroit employee what Ranmar says is correct, the two stroke will love you back if you drive it like you stole it!

Sometimes (depending on what exact engine you have, saying "8V92" is like saying it's a Ford V8, doesn't really provide much info) a horespower increase can be as simple as an injector change.

I'd suggest you talk to a knowledgeable marine engineer, someone like the Lawson boys at Pro-Marine or M&J Engineering. They will be able to guide you as to what gains can be made, and what power increase can be achieved. It might be relatively simple, or it might be cheaper to buy a new boat.

Out of interest, what maximum RPM are you getting out of her in gear? Sometimes if the prop match is way out a new prop can make a world of difference.

Good luck,

Browny.

Posts: 8

Date Joined: 20/12/11

 Good call Browny. I will

Thu, 2016-09-29 18:28

 Good call Browny. I will check out the details with the guys you mentioned. Cheers

Browndog's picture

Posts: 580

Date Joined: 10/04/12

8V92

Thu, 2016-09-29 19:12

If yours is the twin turbo 500 hp engine, there may be a relatively easy way to get a few more ponies, the single turbo 8V92TA engines are rated up to 650hp and were quite common in cray boats, you might be able to pick one up for a reasonable price and it should make for a relatively easy repower as mounts, flywheel details etc are the same. You would need to upgrade the exhaust and play around a bit with raw water plumbing etc.

What RPM are you getting now?

Posts: 5738

Date Joined: 18/01/12

 8/92's are a strong engine

Thu, 2016-09-29 20:00

 8/92's are a strong engine and as said you could find one for next to nothing, see MTU maybe?

But if its glass over ply, you may end up throwing money in you will never see again.
Solid glass Westcoasters are legendary, not so sure about glass/ply.
In any case Id be astonished if you were able to insure it unless the engine change is documented by a Naval Architect/engineer

____________________________________________________________________________

 Give a man a mask, and he'll show you his true face...

 

 

The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.

 

Dale's picture

Posts: 7930

Date Joined: 13/09/05

Thu, 2016-09-29 20:08

 A non turbo 8v92 are only good for about 360hp, but pretty well bullet proof.

____________________________________________________________________________

"Just because you are a Character, Doesn't mean you have Character."

Mr Wolf

 

 

Posts: 8

Date Joined: 20/12/11

 Thanks guys.  Reaches about

Thu, 2016-09-29 20:24

 Thanks guys. 

 

Reaches about 1800 rpm. 

I dont think it is glass over ply. I think it is solid glass hull with timber support frame internal which is fully glassed in.

Useful to note about the single turbo engine. 

Posts: 5738

Date Joined: 18/01/12

 yep thatd be right.We had

Thu, 2016-09-29 20:47

 yep thatd be right.
We had one called Starfire for a couple of years as a tuna longliner and covered Rankin Bank to Esperance over a few years, strong boat.

Theres some photos on here of it somewhere

____________________________________________________________________________

 Give a man a mask, and he'll show you his true face...

 

 

The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.

 

Browndog's picture

Posts: 580

Date Joined: 10/04/12

RPM

Thu, 2016-09-29 21:53

Sounds like it's not propped right. You should be getting at least 2,100rpm, maybe even 2,300. (It's been a while so I can't remember the exact numbers)

Get your engine model number & serial number (Model will read 8082*7400 or similar, Serial 08VF123456 or similar), and even injector model if you can (pull rocker cover and check tag, should read "N70" or similar) and call Penske, they should be able to provide an engine curve showing horsepower/rpm.

If it isn't getting it's rpm, it's either down on power, over propped or has a dirty bum. If it's 500 hp at 2,100rpm, it may only be making 400hp at 1,800rpm and can't turn the prop.

I'd suggest you sort your current setup out properly before spending money chasing more hp with an engine change.

Browny.

Posts: 1392

Date Joined: 08/01/09

gearbox might not be

Fri, 2016-09-30 05:20

 transfering the rpm to the shaft efficiently!

____________________________________________________________________________

FEEEISH ONNN!!!

ranmar850's picture

Posts: 2702

Date Joined: 12/08/12

Browndog is right

Fri, 2016-09-30 07:21

 You should be able to cruise at 1900. I'd be looking for 2200-2300 max. Prop could be the problem, or it could be a fuel system thing. I ran an 8V92 single turbo rated at 500hp in a 42 foot ali hull, quite light, and it would hit 2250 from memory. We bought the boat from the original owner, 1900 hrs on motor and hull, and it had spent it's life being run at 1600-1700, as he didn't work far away. I travelled more, and bumped it up to 1900 for cruise. It smoked and didn't seem to like it, but after just a few working days was a much happier motor. They are pretty thirsty, but also pretty reliable.

That old hull will be pretty heavy, I think you would be really asking a lot of anything to hit a 20 knot +  cruise speed with it. You'd be surprised how quick 18 knots feels after doing 12-14, if you can get that motor running and propped  right ( assuming it is not derated), you should be able to see around that. As Browndog says, it could be a case of different injectors and a fuel pump readjustment. Just be prepared for the fuel bills

Posts: 8

Date Joined: 20/12/11

 Thanks guys.  Sadly however,

Sun, 2016-10-02 13:10

 Thanks guys. 

 

Sadly however, the Detroit is gonna go. It has seen better days and it is time for the long budgeted new engine. So does anyone have a feel for what cruising speed I might achieve if I put a 800 hp engine in her?

 

thanks

Ian

 

 

 

 

Browndog's picture

Posts: 580

Date Joined: 10/04/12

Homework

Sun, 2016-10-02 19:59

You need to do your homework. You could put 2,000 hp in and still find you get the same speed. Or you could sort what you have and pick up 8 knots. Talk to some marine engineers, they will set you straight.

Cheers,

Browny.

carnarvonite's picture

Posts: 8622

Date Joined: 24/07/07

800HP

Mon, 2016-10-03 05:08

Mate had a big Fiat V8 rated at about 800hp in a 50foot Westcoaster, cruise 17 flat out 20 knots

It all depends on hull speed, once you reach that it takes mountains of horsepower for only a small increase in speed.

Posts: 8

Date Joined: 20/12/11

Thanks

Thu, 2016-10-06 17:54

Thanks everyone for your assistance. I will do as suggested and consider the old Detroit a little more closely. Also I appreciate the experience and help you all bring to this forum. 

 

Best regards