Tsunami/bracket power options

[1bayouboy]

Still looking at the options for powering my '74 Tsunami....
I'm planning to build a bracket with minimum setback for the engine
choice. It'll be twins and this is the list so far. Weight
is from the manu websites. Prices approx from Ed's just for comparison.
I'm not sure what the difference is between the Yam HPDI and the VMAX HPDI.


Merc Optimax
135, 150, 175HP same block and weight
weight 431lbs
$7500, $10000, $11000
Smartcraft available on all

Zuke 4S 140HP
weight 415lbs
$8000

Evinrude ETEC
115, 150HP
weight 375lbs
$8000, $11000

Yamaha 150HP HPDI
weight 450lbs

VMAX 150HP HPDI
weight 450lbs
$10000

Yamaha 4S
115HP
weight 390lbs
150HP
weight 450lbs


An offshore trip here in Charleston is about 60 miles
one way plus trolling all day. So I'll get the largest
fuel tank I can reasonably fit. I plan to remove the
in-deck storage/fishbox and also move the tank back a little.
I really liked Strick's tank with the rigging channel down the
side. I'd like to be able to get to 140-150gals of fuel.
I'm going to put a hardtop on it and that will add more weight to
the front....but I'll keep it as light as possible. Moving
the tank back should offset that, along with mounting the
engines farther back. I'm a little worried about the floor
height....but I don't plan to raise it at this point since it's
solid all around.

On the Merc's, they all use the same blocks and have about the
same weight. I think I'll be fine with any of them with a
flotation bracket. Very powerful engines for their rating
from what I read.

My question now is what's reasonable performance WRT to fuel burn
and weight. Would twin 115s be a total dog...?? The twin 135 Optimaxs
are probaly closer to 150HP from what I read....but if I'm
going to have the weight why not get the higher rated and go with 150s.
I really like the Smartcraft technology, I have it on an I/O on another boat.

Everything I hear about the zukes is good....price is about the same
as the Merc 135s. Not sure about computerized guages for the zuke.


I think 115 in a 4S would be too little power but it is 120lbs less weight.
The HPDI 150HP are more weight than the Merc's, but the engines have a good
rep.

The ETECs are the lightest, but most expensive. I'm not sure about the
rated HP versus performance on them and whether twin 115s would be enough ponies
in the ETEC. And like the mercs, if the weight is the same why not go bigger...
except for the $6000. Again not sure about their guage/computer technology.


At this point my two choices are the zuke 140s or the merc 150HP or 135 optis.
But I'd really like to hear about anyones experiences, performance, etc.
If the performance of the 135s is actually pretty close to the 150s....may as well
save the $5000.......

[Bushwacker]

BRP is sandbagging on the ETEC HP ratings! The 150 (which weighs 427 lbs dry)is really ~165 and the 225 is really a 240! (This is from the HP/Torque curves in BRP brochures) NMMA requires the advertised HP to be within +-10% of measured, so I'd guess the 115 is closer to a 125.

[1bayouboy]

I must have been looking at the 115 ETEC for the weight...thanks. I'm leaning to the Optimax....

[Bushwacker]

The June 2006 issue of Powerboat Reports had a 150 hp shootout on identical 20'boats, ETEC & Optimax vs Suzy, Honda & Yamaha. I put all the results in a spreadsheet that I can send you if you'll send me your e-mail address.

[JohnB]

Given the distance you have to travel to fish, it sounds like your looking at twins. I know 2 guys that have switched from transom mounted single 250's to twins on a bracket that have said if they had it to do over again, they would of gone with a single 275/300, for fuel burn, balance, maintenace, and cost. One went with etecs, the other with suzukis. Make sure you have alot of floatation on the bracket, especially for following seas. If you lose one motor, with much weight in the boat, I doubt you will get it on plane with a single 150 engine. IMHO, the 23' do better with a large singe engine, but if you need the security of twins, with a BIG floatation bracket, you will probably be happy. Most of the etecs I have heard of either crap out in the first 50 hours, or run forever, with no problems. Price wise, it is hard to beat the suzukis, and the optimax's are pretty strong too.

[1bayouboy]

Thanks JohnB......I just like the safety of twins. I currently have a 24 I/O WAC that I added a kicker bracket to....just so I can aim for home even if only at 6 knots.
Twin 150's would be good power I think, especially in the Opti. I'm building the bracket ala Strick and Big, so I'm going with a wide tub that roughly follows the contour of the hull about 3-4 inches up at the keel panels, less at the mid panel. I haven't calculated the flotation yet, but
it should be at least 2-300 lbs, and with the extra width
it'll add up fast as the stern sits deeper.

[JohnB]

I am not a marine engineer, but I would think 400 pounds would be the min. for floatation. These boats have a funny way of squating down in following seas. I think I remember seeing some specs on the Hermco twin brack that it had 400 pounds of floatation on the twin bracket.

Almost all the engines your looking at are south of 400 pounds, 2 will be over 800 pounds. Personally, other than the gas consumption, I like the merc 250 efi, weighing in at 472 pounds. About 50 pounds more than most of the 150s.

I put a post up on trying to find the "optimal" bracket height for the armstrong I am putting on. There seems to be a lot of discussion, but not much real world experience.

[1bayouboy]

I've looked at the Hermco bracket.....Mine should have a little more flotation because I'll angle it down at the
point between the inner and middle bottom panels. I think when I calc the flotation it'll be okay. A pair of old 150 evinrudes came off it....they were probably 300lbs each.

With a bracket 28 inches long and 52 inches wide, once it's dep enough to have that size rectangle submerged, you displace 52lbs of water for every inch it sinks.

[warthog5]

The unknown is, how much will it sink down.

[Snookerd]

I think I remember seeing some specs on the Hermco twin brack that it had 400 pounds of floatation on the twin bracket.

The twin Hemco bracket is 800+lbs on flotation. I would be interested to see what the flotation is on the ones being built on CSC.