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Author Topic:   70 HP Nissan setup
SpeedBump posted 06-19-2003 09:30 AM ET (US)   Profile for SpeedBump   Send Email to SpeedBump  
I have a 1970 Nauset rigged with a 1998 70 HP Nissan. Two six gal tanks under the mahogony consol, battery in rear. Not sure of prop size but it is a standard 3 blade aluminum issue for that motor with clipped ears.
The boat set up is basically good. great power when on plane and kicks butt between 3800 and 5400 rpm. It is truely giddy-up time with two people on board. I am adding a mahogany stern seat for cruising with the wife and 2 kids to ease the bump da bump experience on Barnegat Bay. I am sure that the dymanmics of the ride will be greatly improved for my passengers but am concerned with weight distribution, especially at lower speeds when the boat may not be on plane. The seat will add @ 40lbs, wife and two kids @ another 225lbs, miscallanious gear will bring the weight increase to @ 300lbs. The motor is dealer mounted flush on transon, i.e. not raised 1 or 2 bolt holes as recommended in other posts. I am expecting some hole shot issues with the added seating and passengers in the rear. any suggestions would be greatly appreciated. (leaving the wife and kids behind is not an option, at least 50% of the time :-) )
Bigshot posted 06-19-2003 09:47 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
How old are the kids? When I was a kid there was no way I was sitting in the stern. The bow is where the fun is at. With that you may not have that much weight back there all the time.

Where on Barnegat bay, I am from Harvey Cedars.

SpeedBump posted 06-19-2003 10:03 AM ET (US)     Profile for SpeedBump  Send Email to SpeedBump     
BigShot- kids are 10&13- they are OK with riding in the front but as you know the bay gets very choppy from @ 11-4 and riding the front seat can be a rough ride. I hail from Forked River, I stay moored in a cove at the entrance of the river do most of my solitary fishing in between BB and BI and the channel out to the light house. Myers hole is a favorite as is the inlet. don't do much off shore. I travel a lot over to little egg harbour and fish the channels near holgate and the inlet. Makes for a great day trip. Up until this year did all this in a 1968 classic with a 40 HP yamaha on a custom jack plate. hence my user name.
bsmotril posted 06-19-2003 11:42 AM ET (US)     Profile for bsmotril  Send Email to bsmotril     
Could you move the battery up front? That would offset one kid.
Bigshot posted 06-19-2003 12:59 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Ahh....Forked river. the only time they pronounce the "ed". Snakes have forked tongues but are not pronounced fork-ed. Very odd.
SpeedBump posted 06-20-2003 09:20 AM ET (US)     Profile for SpeedBump  Send Email to SpeedBump     
I have been considering moving the battery forward, have plenty of room in the consol. however the tunnel is getting pretty full of cables ETC.

Have also considered adding a Sting Ray, DolFin,whale tail or other type of lift devise. Had a plastic dolfin on my classic 13 and it worked very well. Given the increased size of boat was not sure how effective this type of devise would work.
Will be installing the new seating Saturday, so I will decide on other options after a couple of days of testing.

BigShot- I also have wondered about the odd pronunciation but it doesn't matter how they pronounce Forked River, I pronounce it Nirvana when I am on the boat!!

Salmon Tub posted 06-20-2003 08:18 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
SB, As I recall, that 70 is about 225-240 lbs, and that figure may include weight of the controls... (packed wieght). I have the 90 on my rear, and that goes at 300-310 lbs. With the bench in back, you will be fine, as far as static trim. You should have no problems while underway, and should actually get a bit of a better ride. The only difference you might see is if you drift with the extra weight in the back, but, even then, I have no problems with a 20 gal. bait tank in back.
SpeedBump posted 06-21-2003 04:09 PM ET (US)     Profile for SpeedBump  Send Email to SpeedBump     
Sal you are pretty close on the weight- 253 lbs as listed in the manual. I will be looking for the prop pitch on this elephant ear prop. as I recall it is a 15 pitch. I downloaded the propeller basics and performance links and I'll be on holiday for a couple of weeks with the boat. I hope to be running some tests to see if I can get the best set up for all around use.

Thanks for the input on this.

SpeedBump posted 06-21-2003 07:46 PM ET (US)     Profile for SpeedBump  Send Email to SpeedBump     
My memory isn't so good today must be the effects of 12 solid weekends of rain here in NJ!!! My prop pitch is 17
Doing some quick math using the performance formulas I should be able to get up to @ 50 MPH WOT. This is based on 12:28 (2.33) reduction, 5850 RPM WOT, and a 17 pitch. not that I really want to in 16'7" boat..
I don't think the extra weight from the seat will be a bother. will let you all know..
Bigshot posted 06-22-2003 07:45 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Calculations are way off. There is athing called slip which should be called drag. You will be LUCKY to hit 40mph with no weight and propped right. Figure 35-38 as the norm.
SpeedBump posted 07-02-2003 10:13 PM ET (US)     Profile for SpeedBump  Send Email to SpeedBump     
Bigshot- you are correct about the top speed. readings based on my Hummingbird 25 - which I don't think is very accurate- my top speed was 40 MPH on dead calm water WOT with myself and one of the kids. This was after I installed the stern seat transforming my Nauset into an Eastport. The big difference with the stern seat is certainly the vastly improved comfort level on the choppy Bay. no real setbacks in performance, either top speed , hole shot or getting up on plane.

now i am trying to figure out what the most efficient crusing RPM is. This NIssan 70 is a thirsty motor to run.....

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