I need some ideas for attaching my pump to the hull. I tried just straight epoxy but the pump is near an area with a lot of things around it (batteries and CO2) and always seems to get knocked off. Any thoughts?
I like bonding threaded inserts into the hull and then making a strap over the top of the pump housing and fastening the strap into the threaded inserts...
It is probably a good thing the pump won't stay bonded to the hull. It is VERY good to have a removable pump so you can clean the pump screen of debris. I usually build a low frame for the pump to sit into then strap it in place with screw hooks in the hull bottom and straps. Zip ties actually work well. Rubber bands don't. Heh.
I like brass straps. I've seen people use rubber bands, but I've also seen the pumps held in by those rubber bands get torqued at an angle, which has affected their pump priming.
I tried many methods for this and found, like Mike said, that taking the pump out was very important. I needed to be able to clean the screen under it. In the past I tried many things and even epoxied in some posts to hold the pump in place. For some reason when working in the boat I always broke them. Then I got a tip to make some posts and use a plate with a hole in it to hold down the pump to allow it to be easily removed with 4 screws. It was also suggested to use marine goop to hold the posts down. I immediately dismissed this as I had rigid thinking in that if you wanted it to be structurally sound then you must use epoxy ( but it broke off all the time..). So I made a plate and attached wooden posts, dry fit it to bet the plate level, sanded and cut on the posts until it was perfect. Then I sealed the wood and once cured I mounted the pump into the ship with the plate and posts and gooped it in. I put some under each post before setting them onto the hull and then ran a bead around each post (using a coffer stirrer where the tube wouldnt go) and once done it was rock solid. It also has a little shock resistance AND is removable without affecting the hull. I have been very satisfied with it and of all the designs I have tried this was the easiest to build and finish. Once I decided what to do it took about 2 hours.total (not counting drying time). I did use threaded inserts on the posts so that I could remove and replace the screws over and over. I used 8-32 screws because the 4-40 were to small to work with and when I dropped them they disappeared into the ship. I made this mount wide to make sure I had clearance to remove the motors and also to accommodate 2 pumps in the future which has already happened. The posts are very strong but it took about 2 days to completely dry. Hope this helps.
I like the idea of bolting it to the hull. Will the bolt heads cause a lot of drag on the bottom? I also dont like that idea because it doesnt look very good. 4 bolt/ screw heads sticking out the bottom of the hull.
More than likely the bolts screw into blocks attached to the bottom (inside) of the hull instead of going through the hull.
Looks like a windshield washer fluid pump. I wonder if it's positive displacement? Not trying to hassle the estimable Mr. Tyng, but a lot of those pumps are positive displacement. Looks like a great install in a tight space, for sure, though.
It probably is. Big gun guys use the positive displacement pumps quite often I've heard. Obviously, in small gun they arent allowed. EDIT: quoting appears to be somewhat broken now.
How so? Steve actually has a thread about the pump over here: http://www.rcnavalcombat.com/Forum/...fault.aspx in which he takes it apart and clearly shows an impeller.
When I tried to quote it was showing three lines of quoted text. I'm not terribly concerned about it.
Odd. Don't know why it would do that. I have gripes about the editor and the way quotes display (or don't in some cases) - makes it difficult to work with.
Sometimes it works better then others. Like you, I'm not thrilled with it, but it is what it is. It's not really worth complaining about
It's a windshield washer pump for a 2000 Jeep Wrangler, $15 from Autozone. It's been "sligthly" modifiied.
If it's got an impeller (which someone says is shown in a build thread somewhere) it's centrifugal, yes?
yes. Impellers with any shaped vanes (straight, curved, etc...) are centrifugal. Diaphrams, gears, screw, peristaltic, rotor, roots, etc... are all postive displacement. Das Butts
I duly searched for Steve's COTS pump thread... the Jeep pump is indeed a centrifugal pump. Four plade impeller.
