[Motomatt68]

I have a bare aluminum sprint boat hull that I have going to be using for rivers and pleasure boating. Alot of the rivers that I will be using it on are shallow and full of silt and gravel so I decided to put a Hamilton 2stage pump in it. I would like to get all the room I can inside the boat so I was thinking of setting back the pump and engine. These boats are usually run with multistage axial flow pumps like the hamilton but the have the weight of the engine centered and a skeg towards the front of the keel to aid in quick turning (supposedly up to 3-7G's) I really have no use for that kind of performance in the corners but at the same time I dont want to ruin the ride. How far back can I safely set the pump and engine back in a boat this small? (13.5')

Here is a video of a very similar boat.

and a video of more what I am planning on doing with it.

their boats are 2' shorter and have smaller engines and I wont be quite so extreme I do plan on hitting some rocks and skidding across a little gravel.

Any ideas would be appreciated, Matt.

 

[Canuc]

matt why don't you get berkeley , shop for a decent core a rebuild kit and a new alum. A imp. and you spent $1500 and your hull has a berkeley intake:grin:

 

[Motomatt68]

I already have a berkeley j12b with an a impeller. I also have the hamilton. I am still bouncing between the two pumps but keep leaning towards the Hamilton because it will be better in aerated water,at pumping gravel, planing at slower speeds, and hole shot. If I am going to want the Hamilton at any time in the future now is the time to do it when the hull is bare and it is not a big deal to swap. I figure that the guys here would know the most about how the boat would handle if I put everything back to make more room in the boat.

Matt.

 

[Motomatt68]

Looking at your avatar I am guessing that you know a thing or two about what I am talking about. I assume you have a berkeley style pump? AT SD-309? I am in no way against berkelys. I am just asking questions and hoping for an epiphany.

Matt.

 

[Canuc]

ya my jet is a berk-at style . not against what your saying about the pros and cons of the two types of pumps for the kind of use your describing but think you should try the berk first as i think i read on another forum your hull had a berk intake in it . have you decided on power yet? keep it simple and light with some hp and unless your boating where you have to dredge a channel the mixed flow will perform well .

 

[Motomatt68]

You probably have seen me on meanchicken, moab21. I do have a Berkeley intake and since I first posted this I looked at it and noticed that it is already set back some. With my current set up on my 21'er I get a decent amount cavitation when the water gets choppy so I would rather go with the Hamilton. And now seems like the time to change if I am going to. The Berkeley would be easier and no doubt work well especially with the deeper vee as a lot of my problem with cavitation on my other boat is probably due to how flat the bottom is. I just hear so much about how well the hamilton multistage pumps work in the situations that I will be using this boat in. Haxby was pretty adamant that the Hamilton would be much better for my situation and he is a fan of the AT. But still the Berkeley would be easier. I have both pumps and can do the fabrication myself.

The engine I have is a mid '80's Volvo 5.7l that makes around 260 hp and redlines at 4400. It is all iron but it is what I have. I have thought about using a smaller lighter engine but don't want to put the work or money into getting something else.

Matt.

 

[Canuc]

your cavitation problem with the 21 IS THE BOTTOM and the size of boat , not an issue with a light v boat if the keel and intake are right . the hammy will have better acceleration but again with the small boat not huge . the hammy will still be focked if you fall off plane in shallow water , but will keep and or get going with less . the berk will still bump over a bar here and there with the right grill if you can slide to deeper water with your foot out of it. the hammy will cost more to set-up and maintain especially if your pumpin gravel , i'd put the money into alum. heads , intake and cam for the 350 . any pics of your hull , intake grill etc?

 

[Chop Shop]

I am building an aluminum too. Its a 19 foot Vhull. Set back berkeley.

Ive noticed the go fast guys like the simple cheap AT berk pumps.

The fishin boat, run the most CFM river kinda guys like the expensive hammys.



In a 13.5 foot boat, I would be looking for more performance or less weight in the engine department.

Sprint boats are small and run SBC too, but not in white water. They run the engines toward the middle of the boat.

A sbc mounted inthe back of a 13.5 foot boat would make me nervous. Thats alot of weight bobbing if the engine dies. One bob, GONE.


10 seconds to sink once the fire is out. Crazy jet boat race crash boat sinks - YouTube

With no fire, the boat is going to go back down river SBC end first. Not good.

 

[Canuc]

forgot to mention the speed and cruise efficiency you'll loose as soon as you cut the bigger hole in the bottom . the sprint boats use a lot of hp for how fast they go , but use the high volume of water for the acceleration and handling they have with the boat glued to the water , probably not how your going to use your boat :hmmm:

 

[Motomatt68]

Canuc and Chop Shop thanks.

Your last two posts are the reason that I ask around. On MC the answer is almost always Hamilton and "if the manufactures arent doing it why would you?" There is alot of knowledge there but not always thinking out of the box. Berkeley is definately the redheaded step child of pumps over there. I understand that you do what you know and use what works. I do think that it is funny that guys on this forum spend huge amounts on engines and dont get why the whitewater guys spend so much on pumps and the whitewater guys dont get the need to pimp out an engine and can spend thousands on a pump without blinking. I guess it is offroad compared to dragstrip. This is alot of why I am having a hard time putting the berkeley in the boat.

Canuc, the Hammi makes more sense on alot of levels but not financially and the AT I have in my big boat really makes it move well and I use it on the same river I will be using the small boat on. I will give te berk a try first then change it next winter if I still want to. I already have a couple of nozzles, a stomp grate, and a diverter for the Berkeley and I would have to spend some money on the Hamiltons that I have.

I dont know what to do with the engine since it is what I have and I know that it is heavy. When I built my BBC I weighed it at 690lbs with aluminum heads, intake and exhaust. I cut 90lbs with the heads alone. I know aluminum parts on a sbc will not make as much of a difference but I will have to see.

Chop Shops video makes a very good point about that much weight in the rear and solves the question of the setback engine. I will leave the intake where it is for now.

I dont have any good pictures that I can find now but I will post some when I start building.

Thanks,Matt.

 

[shakescreek]

"but keep leaning towards the Hamilton because it will be better in aerated water,at pumping gravel, planing at slower speeds, and hole shot."

I have used both berk style pumps and multi-stage hammys a considerable amount on shallow braided gravel bottom rivers, and I would have to disagree with you Matt on the hammy being better at pumping gravel. Put a stainless impeller in the berk and in my opinion it will pump gravel with less damage to the pump than the hammy will. I've destroyed quite a few impellers and stators in my 3stage hamilton and pumped enough gravel through my berk style pumps to be convinced the berk style impeller stands up much better to that sort of use. Stators also seem to stand up better to gravel in the berk pumps than the hammys. I agree on the aerated water, the hammy will definitely be better there. Planing at slower speeds, and hole shot in a small light boat will be too close to call. In a bigger heavier hull the advantage would go to the hammy. The hammy will also be better at handling debris like sticks, leaves, moss, grass ect without loosing performance, but they don't stand up well at all pumping gravel.

 

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"but keep leaning towards the Hamilton because it will be better in aerated water,at pumping gravel, planing at slower speeds, and hole shot."

I have used both berk style pumps and multi-stage hammys a considerable amount on shallow braided gravel bottom rivers, and I would have to disagree with you Matt on the hammy being better at pumping gravel. Put a stainless impeller in the berk and in my opinion it will pump gravel with less damage to the pump than the hammy will. I've destroyed quite a few impellers and stators in my 3stage hamilton and pumped enough gravel through my berk style pumps to be convinced the berk style impeller stands up much better to that sort of use. Stators also seem to stand up better to gravel in the berk pumps than the hammys. I agree on the aerated water, the hammy will definitely be better there. Planing at slower speeds, and hole shot in a small light boat will be too close to call. In a bigger heavier hull the advantage would go to the hammy. The hammy will also be better at handling debris like sticks, leaves, moss, grass ect without loosing performance, but they don't stand up well at all pumping gravel.

Good Point across the board. A pre-loader would help with some of the problems stated. Th full set back I would think not good as the hull provides the highest point of lift (thus the std. setting or close to, would provide the cleanest pass thru position) No pump is a good rock hunter, and no Axial can ever obtain the on -plane or top speed of the Mixed Flow- Just a Fact and function in design!