Baja_man

I am adding a sea strainer and mechanic is asking if I want external pick through the hull or just keep the dual pick through the bravo unit. What is the advantage of either? I am also adding a Stellings box and will use it at the highest raised dimension. I have heard that with a high "X" it can suck air through the bravo unit. An input would be helpful.

fireboatpilot

I've never seen a strainer fed thru the drive so in answer to your question I would say yes you are going to want to install a new pickup. Placement of the pickup is critical. Your going to want to make sure that the strainer has a constant supply of good water at all times and speeds. There are all types of pickups to choose from but I don't know which is best. My Scarab had them in the transom and my cat has them in the bottom. I wanted to install pickups in the transom on the cat and I was told not to move them because we would then have to trail and error a new location and depth for them so there are several variables to factor in besides looks which was my first concern. I wish I could be of more help and the drive water inlets might work but I believe that the purpose of the strainer is to filter the water before it gets to the pump, not after. My drives had the pumps removed and filled. I think you will need a raw water pump too?

jeff1000man

Use both. The water moving though the drive helps to keep it cool.

That bravo pick up actually only flows 3/4" through the gimble.
You can plumb a sea strainer through a drive. I have seen a lot of them that way.

I am using both pick ups, and then I have a pressure releif valve for the extra water pressure. It is overkill, but why not??

t500hps

A buddies boat is rigged with transom pick-ups feeding strainers and the bravo water pick-ups loop up and back out the transom to dump water onto the top cap while underway......great set-up IMO.

FIXX

Fireboat? Waterpumps in a bravo? you had your's filled? bravo's have external pumps as far back as i could remember..are you running alpha's.not trying to bust your BBBB's but somthing dont sound rite

fireboatpilot

Sorry for my tongue tiedness (made up word). What I meant to say is that the low water pickups in the bravos where filled in and not in use anymore. And yes he will need sea water pumps. I got lost in the explanations. I will be running Imco SC's this season. The point was that the location of an external pickup is very important as well as the depth of it into the water. There's a little science involved. Thanks for helping me.

Young Performance

He won't need new sea water pumps. He already has one, why would he need another?

The problem you may run into with using the drive pickup is that it is a dual water pickup. With the ext. box set on the highest setting, the side pickups on the drive could actually suck air pretty easily. What happens in the dual water pickups is that water comes in the low pickup and actually comes right back out the side pickup, causing a lack of water. If you use the drive pickup, you may have to plug the side holes. I drill and tap them and install a 5/16" set screw with some red Locktite. You can also open up the low pickup to help it flow more.
Which is the right setup for you depends on what you have. Some boats do better with the drive pickup. A transom mount pickup will actually leave the water before the drive will. That is another benefit of a strainer. It is a reservior for the engine to pull from. If you have a smaller boat and you boat in rougher water, you may be better off with the drive pickup. The other big factor is hp. If you are making quite a bit of power, than the drive pickup may not be enough. Give me a little better idea of what you have and maybe I can give you a definitive answer on which route to take.
Eddie

jeff1000man

Eddie,

Since you are on the subject, What are your thoughts/ feelings on using both pickups into a single strainer? Obviously there will be more water available than the pump can take. Pressure releif valve can handle that.

Will the pressure from the transom pick up keep water from flowing in from the bravo?

Boat is small, so I was thinking the same way you were that when the boat was coming out of the water, it could still draw from the low water drive pckup?? Or would it just suck air from the transom pickup?

Reason I am putting thought into it is because I am using the 2 stage pump, and the hole coming through the transom assembly is not very big. I am trying to get the true 1 1/4" water flow to make sure that the volume is there when it is needed.

THanks, Jeff

Baja_man

Thanks, good Info. Currently I have a 25 OL sock 496 H.O. It is getting a Stellings box added and will be run in the highest "X" dim setting. Stock height is 6 1/2" so with box I am thinking around 4"??? No big HP till prolly next year (2011)

Young Performance

The water could potentially come back out of the drive, or the pickup for that matter. I can see where one could overpower the other. I guess it will all depend on what the strainer pressure is. What I do when I use a 2 stage pump is to feed it with a 1 1/2" hose, instead of 1 1/4" hose. The 1 1/2" can keep up with the 2 stage pump. If you are using both stages for the engine, the exhaust usually restricts the flow enough so that the pump will never empty the strainer. It has always worked well for me. I always at least check strainer pressure to see what it is. This gives me an idea of what's going on. Is the pump taking all of the water?(low pressure in strainer). Is the pickup to deep causing high pressure in the strainer?(high strainer pressure). This will tell me what to do. I like to see around 10 psi in the strainer. This ensures the pump will always stay full of water. In your case, I would just use the transom mount pickup for the engine and use the outdrive pickup as a drive shower. You have to do something with the water from the drive. You don't want to just plug it up because it will want to blow water back out of it and could cause the prop to cavitate. Best case it will increase the slip by not giving the prop clean water. Hope this helps.
Eddie