Hendo's Randall 35 Cray Boat complete rebuild, Perth, Western Australia

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I prefer direct drive pumps. It's important to match GPM (Gallon Per Minute) flow rates at the same RPM. If the pump pulley and the drive pulley on the engine are the same diameter then you only need to match the pump flow rate. If the pulleys are different size, you may need to change pump size to insure adequate water flow.

Ted


Hi Ted,
Thanks for you post mate. How should I go about working pump flow rate required? I found this on google.

Does this sound right to you?

"65-70ltrs per minute for each 75kW of engine power"

Thanks for your help mate.
 
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I would start by identifying the pump you currently have. You should be able to find a flow rating tied to an RPM. Let's say your pump produces 40 lts. per minute at 2,000 rpm. Let's say the pulley on the engine is 6" in diameter and the pulley on the pump is 4" in diameter. As engine pulley is 1.5 times bigger in diameter, it will turn the smaller pump pulley 1.5 times faster. So, if the engine is turning 2,000 rpm, the pump will be turning 3,000 rpm and theoretically pumping 60 lts. per minute. So, if this were the case, I would be looking for a 60 lts per minute pump if I were going to direct drive it. This all assumes you had adequate flow with the original pump.

To recap:
You need to know how much flow at what engine RPM you had.
You need to select a pump that will give you the same flow at that same engine RPM.

You can have 4 different engines that will produce 75KW at different RPMs (1,800, 2,400, 3,000, and 3,400). A direct drive pump will likely only produce optimal water flow for 1 of the 4 because of the RPM. The others, theoretically need larger or smaller pumps.

Can you identify the make, model, etc. of your original pump?

Ted
 
Matt: If I a remember correctly you have a Perkins. A lot of those have all been marinized and have gear pumps. Perkins is still pretty well supported on this side of the pond. What engine do you have? It may have already been spec'd with an off the self pump.
 
I would start by identifying the pump you currently have. You should be able to find a flow rating tied to an RPM. Let's say your pump produces 40 lts. per minute at 2,000 rpm. Let's say the pulley on the engine is 6" in diameter and the pulley on the pump is 4" in diameter. As engine pulley is 1.5 times bigger in diameter, it will turn the smaller pump pulley 1.5 times faster. So, if the engine is turning 2,000 rpm, the pump will be turning 3,000 rpm and theoretically pumping 60 lts. per minute. So, if this were the case, I would be looking for a 60 lts per minute pump if I were going to direct drive it. This all assumes you had adequate flow with the original pump.



To recap:

You need to know how much flow at what engine RPM you had.

You need to select a pump that will give you the same flow at that same engine RPM.



You can have 4 different engines that will produce 75KW at different RPMs (1,800, 2,400, 3,000, and 3,400). A direct drive pump will likely only produce optimal water flow for 1 of the 4 because of the RPM. The others, theoretically need larger or smaller pumps.



Can you identify the make, model, etc. of your original pump?



Ted


Ill have a look at the pump tomorrow mate.

Just out of interest, can ya go too high in pump volume? I'm looking at a jabsco 6400 series that pumps 200ltrs per minute at 1500rpm.
 
Matt: If I a remember correctly you have a Perkins. A lot of those have all been marinized and have gear pumps. Perkins is still pretty well supported on this side of the pond. What engine do you have? It may have already been spec'd with an off the self pump.


Hi mate. Yeah she's a Perkins 6354 but not an original marinised one
 
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Too late to go keel cooled? I saw a Gardner that had a keel cooler and a small pump for a wet side exhaust. Couldn't go out the transom. This way you don't need heat exchangers (except for the keel) and you only have a small amount of water for the exhaust, therefore a small pump.
 
WOW, Thank You Matt for the picture # 6 From today. Side view of the whole boat. I can see the elegance of your design of Solstice. What a beautiful boat you have there. Great flow of shapes and lines along the sides. I haven't quite put it all together in my head until now. Can't wait to see the same perspective in a photograph when you get the final paint on it. Carry on.
Dave.
 
Greetings,
Mr. H. Looking good. I like shiny. Seems she'll be ready for paint one of these months...


Hi mate. Yeah not long till HB primer goes on then I can block it back for her finally fairing before primer and colour. Mind you I still need to do the Port side before that happens in its entirety.

Thanks for posting mate, it's nice to hear from you ;-)
 
Too late to go keel cooled? I saw a Gardner that had a keel cooler and a small pump for a wet side exhaust. Couldn't go out the transom. This way you don't need heat exchangers (except for the keel) and you only have a small amount of water for the exhaust, therefore a small pump.


Nothing's ever too late but I won't be keel cooling mate. All the parts are here and working so I'll stick to the set up I've made.

Thanks for the suggestion tho mate :)
 
WOW, Thank You Matt for the picture # 6 From today. Side view of the whole boat. I can see the elegance of your design of Solstice. What a beautiful boat you have there. Great flow of shapes and lines along the sides. I haven't quite put it all together in my head until now. Can't wait to see the same perspective in a photograph when you get the final paint on it. Carry on.
Dave.


Thanks for you message and words of support mate. To be honest there was no real design more so it just happened to end up looking like this lol. I wash I could take the credit for said design but it's a combination of a number of vessels that I admire and wanted. Thanks again Dave. Nice to hear from you again mate.
 
Looks like plenty of raw water from that pump.

Ted


Yeah mate she's a beaut. 200ltrs per minute at 1500rpm. I made an adapting plate (well the plate was already on the engine, I just bored and keyed it) so the pump fits straight to the crank and not via a pulley and belt. Will be a pita when I go to change the belts but I can live with that
 
Tool,
If the lighting was on the hull he could use it for his avatar. I think Matt said his present avatar was temporary.
 
H: are you still considering filling the cutouts on each side with glass/lexan/something for engine room lighting? In your above pics it looks like nothing there yet. Looking good amigo.
Mike
 
H: are you still considering filling the cutouts on each side with glass/lexan/something for engine room lighting? In your above pics it looks like nothing there yet. Looking good amigo.
Mike


Hey Mike!
Mate to be honest the jury is still out on whether or not I'll use them for air intake as originally planned or as Windows.

I'll cut out the Port side to mirror the Starboard side but will wait until I'm a bit closer to finishing before I make my decision. The plan is to get a crane to come in and weigh her then a NA can get an idea of where the water will sit and go from there. At this stage it's just a guess. Maybe it'll work out and if it does I'll leave them as vents, if it doesn't then I'll turn them into fixed windows ;-)
 
Hey Mike!
Mate to be honest the jury is still out on whether or not I'll use them for air intake as originally planned or as Windows.

I'll cut out the Port side to mirror the Starboard side but will wait until I'm a bit closer to finishing before I make my decision. The plan is to get a crane to come in and weigh her then a NA can get an idea of where the water will sit and go from there. At this stage it's just a guess. Maybe it'll work out and if it does I'll leave them as vents, if it doesn't then I'll turn them into fixed windows ;-)

My vote is for engine room lighting, natural light is a good thing, no cost. I wish my boat had it. Keep pushing mate and get her in the water.
 
I saw a picture of just the old boat ribs the other day Matt and was blown completely away by the progress you've made.
 

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