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  #1  
Old 10-18-2009, 05:32 PM
cdavisdb cdavisdb is offline
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Default Re: Seafari 25 performance

Wow Denny, that's fabulous information. Thank you VERY much!

It looks like I can adjust rpm for max efficiency on the fly with a vac gauge, no matter the load.
Looks like 9 inches is near the magic number for me too, about 35-3600 with this load. Bahama trips are my main use of the boat and that means about 1000 lb over what I was carrying yesterday. I'm a little surprised the rpm for high efficiency is above 3400. That seems high to me, a lot higher than a carbed 5.7. Is that a function of fuel injection? Maybe that will change with higher load. One more question on vacuum guages: This one is on the end of what must be 25 ft of plastic hose. Does hose length affect reading?

The low planing speed hasbeen a huge advantage for me, although with the seafari, I won't need it as much. It is mostly the result of the duoprop, but my seabird would plane down to 11 knots, even with a heavy load. It had very wide tabs, which I liked a lot, and they may have had something to do with the low speed. I really hate the single stick control on the seafari tabs and will be changing to a two button soon. Also maybe wider tabs, when my budget recovers a bit.

On props, I will be getting another set, as soon as I figure out what size, and use these as a spare. My wallet howls every time I think about stainless volvo, but I run in shallow water, coral, etc a lot. Think I gotta do it.

Has anybody tried putting extra weight, lead, concrete, whatever, way up in the bow of this boat? The engine sits so low, 3-4 inches below what volvo recommends, that I worry about water intrusion, especially with the idiotic volvo placement of the flapper valves inside(inaccessible)the exhaust pipe. You can't tell if they are working or not. Mine were stuck when I bought it. I'm planning to install 2 inch spacers to raise the risers, but when 3 or 4 guys gather in the stern, the boat sits very very deep. Maybe a couple of hundred lbs in the bow would help keep the stern from sinking so far. Might also damp the roll a little.

Thanks again.
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  #2  
Old 10-18-2009, 05:37 PM
cdavisdb cdavisdb is offline
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Default Re: Seafari 25 performance

Denny, this was not your buddies boat, but you have probably seen it, pretty distinctive, light blue hull, white topsides and bimini, white fish box built out aft of and across the stern.

Brandon, what width tabs do you have on yours?

Connor
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  #3  
Old 10-19-2009, 12:23 AM
seafari25 seafari25 is offline
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Default Re: Seafari 25 performance

I guess a picture is worth a thousand words. This was taken before my cleanup and paint a few years ago.
[image][/image]

I credit my Grandfather for getting those on. I've never run the boat without the plates on the tabs but they are super sensitive when activated. I usually have a list corrected seconds before the weight shift In my younger, crazier, foolish, stupid, stupid, stupid years, usually to impress a young lady...stupid...I would trim port tab all the way down and starboard up and lay the boat on her side, without turning the wheel, at about 20 plus and yell" we're goin over" or some stupid thing like that...anyway my point is, the tabs are effective and...we were all young at some point . Ours are made of steel and are holding up but when I have to replace them, I'll try aluminum.

Well...I guess I gave you a thousand words anyway
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  #4  
Old 10-19-2009, 11:40 AM
cdavisdb cdavisdb is offline
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Default Re: Seafari 25 performance

A thousand words indeed. That pic helped a bunch.

My tabs are a couple of inches narrower and more inboard. Coming from very wide tabs, they don't seem to me to work all that well. I might switch to something closer to yours, but all in good time.

Denny,
I might have to raise the engine box to get 4 inch extensions in there. Food for thought.

I had already looked at the Moesley ballast patent and considered it neat but impractical. I'm rethinking that now after seeing the problem. If I could come up with a bullet proof fill and drain system that was fast, there is room on the keel forward of the seats. Will be doing some calculations on how much weight would be added.

Does anybody know how much room there is under the well between the seats at the aft end of the well?

Connor
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  #5  
Old 10-19-2009, 08:49 PM
cdavisdb cdavisdb is offline
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Default Re: Seafari 25 performance

Just went out and measured, and I'm pretty sure I can get 4 inch riser extensions in without raising the engine box. that makes me very happy. Also got a chance to try straightening out the props. Boy, did I screw them up! Seems like I do something like this every time I buy a new boat.

Interesting info on props vs load. I will have to get a bunch of people on board and get some more data to see
how much relation there is with a duoprop.

Duoprops are different in unusual ways. Look at the props and they don't have all that much diameter, even though, with a total of 6 blades, there is a lot of blade surface to grip the water. What really grabs you is the pitch, its huge. They get away with this by turning them real slow. If you are towing behind the boat and look at the props, you can almost see them going around, compared to just a blurr with other drives. Very distinctive. The slow turning speed reduces cavitation and frictional losses, contributing to efficiency.

I've read several places that fuel injected engines were using very aggressive valve/cam timing/overlap (not exactly sure of the right terms). Bushwacker's comments about my vac results are consistent with that. It also makes the engine more susceptible to water intrusion via reverse reversion, a real nasty for me, with such a deep engine and since much of my diving is drifting with the divers, at idle where rr is worst, stern into the wind and wave. I like the idea of 4 inch extensions, very much.

Connor
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  #6  
Old 10-18-2009, 08:46 PM
Bushwacker Bushwacker is offline
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Default Re: Seafari 25 performance

Hi Connor,

If you're gonna carry another 1000 lbs, which sounds typical of Bahama trips, the props you have may be about right! I had my spare Al prop cupped so that it would turn about same rpm as my stainless prop; when I got over to the Abaco's I would switch my good stainless prop for the aluminum prop to prevent reef rash on my get-home prop!

The rpm for peak efficiency is primarily a function of the cam but the amount of gear reduction and prop design will also affect it. A 4 blade prop will sometimes be more efficient at cruise because it has less slippage, but higher friction losses at high rpm tend to hurt top speed. The duoprop may have similar issues, but it should eliminate all the swirl in the prop wash which should be a good thing.

Both the diameter and length of the tubing will affect TRANSIENT response of any pressure gage, but since there is no flow going thru the line at steady state conditions, it won't affect the reading. When I first hooked up the vacuum gage in my truck, I tee'd into the vacuum line running to the power brake booster with a 1/4" line about 2' long and that was too sensitive - the gage would fluctuate a couple inches as each cylinder fired! Had to put a .060" dia. orifice in the line to stop that!

Sounds like you might want to move those exhaust risers up more than a couple of inches! Having them too low is a quick way to kill an engine! I'd never add weight to a boat just to balance it, but have you considered adding a ballast tank? It would damp roll as well as help adjust longitudinal trim. (Check out Moesly's patent Moesly's Patent on Carla's web site.) He used ballast tanks in the race boats; they worked well and he supposedly designed the Seafari 25 with the idea of using a ballast tank, but sold the company to Potter before he ever built a 25 and Potter evidently never included the ballast tank.
Denny
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  #7  
Old 10-19-2009, 09:48 PM
Blue_Heron Blue_Heron is offline
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Default Re: Seafari 25 performance

I'm glad to finally see a dialog about a 25 Seafari. Thanks, Connor, for posting your performance numbers. I have some thoughts, but understand that these are mostly based on investigation and not actual experience, since the only time my 25 has been wet since I bought it was when I left it out in the rain.

Quote:

I really hate the single stick control on the seafari tabs and will be changing to a two button soon.
If your tabs are Bennett, you might consider their auto trim system, the AC 3000. The rocker switch assembly runs $50 +, which makes the auto tabs that much more attractive. My 25 has Boat Leveler tabs which have a rocker switch almost identical to the Bennett, so I'm assuming the AC3000 will work on them as well.

Quote:

Has anybody tried putting extra weight, lead, concrete, whatever, way up in the bow of this boat? ...Maybe a couple of hundred lbs in the bow would help keep the stern from sinking so far. Might also damp the roll a little.

I understand it is very common to find ballast placed low and forward in these boats. Mine didn't have any, but I plan to place a fresh water tank under the cabin/cockpit sole forward of the fuel tanks to serve as both adjustable ballast, and fresh water for wash down.

Quote:

Does anybody know how much room there is under the well between the seats at the aft end of the well?

The fuel tank compartment ends where the deck drops 6" to the cockpit sole which continues into the cabin. There is a plywood bulkhead under the deck at the transition. The bulkhead in my boat has a cutout that allows access to the space under the cockpit/cabin sole. This space has a sole that sits atop the stringers and tapers in width, and to a lesser extent height, toward the bow. I don't have exact measurements, but I believe I will be able to fit a 38"L x 20"W x 9"H, 25 gallon tank under there which will weigh a little over 200lbs. full. I plan to build a plywood mockup of the tank to test the fit before I order it.

Seafari25, the tandem trim tab setup is very cool and an ideal solution for these variable deadrise hulls. What was used as a linkage between the inner and outer tabs?

Dave
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  #8  
Old 10-19-2009, 10:29 PM
cdavisdb cdavisdb is offline
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Default Re: Seafari 25 performance

A pic may be worth a thousand words, but you have to actually look at the pic. I totally missed the double tab. That is amazing. Ditto on Blue Herons question. Maybe I can do the same on mine.

Dave, thanks for the measurements. I also was thinking water storage before I thought about Bushwackers comment.
If you would like to get together and compare boat notes, let me know.
Connor
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  #9  
Old 10-20-2009, 09:16 PM
Blue_Heron Blue_Heron is offline
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Default Re: Seafari 25 performance

Quote:

If you would like to get together and compare boat notes, let me know.
Connor
Connor,
You're in Sarasota, right? I'll be going down to Bonita Springs on Wednesday 11/11 and returning Sunday 11/15. I'd love to stop by and see your 25 on the way down or back if that's convenient for you. I've never owned an I/O before and I'd like to get the benefit of your experience.
Dave
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  #10  
Old 10-20-2009, 09:59 PM
seafari25 seafari25 is offline
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Default Re: Seafari 25 performance

Quote:
A pic may be worth a thousand words, but you have to actually look at the pic. I totally missed the double tab. That is amazing.
That's funny stuff Connor!

The "plates", as I like to call them, are all one piece 3/16 steel, bent the shape of the hull and welded to make a channel in the middle(can be seen right side of port tab, left side of starboard in above pic). The top of the channel is level with the top of the plate. The bottom of channel is level with bottom of plate but the forward edge is bent(curved) upward so it never drops below hull and also seals the channel from the front. The rearward edge of the top of the channel is cut out to allow better access to bolt it to the trim tab. The plates are each secured with 4 1/4" SS bolts.

Wow that's hard to explain. That's why I hoped a picture was worth a thousand words.. JK...Happy to answer any further questions fellows.

Brandon
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