FC 390 - New Engine

Post Options Post Options   Likes (0) Likes(0)   Quote 700 LTR Quote  Post ReplyReply Direct Link To This Post Topic: FC 390 - New Engine
    Posted: 16 Jan 2019 at 9:42am
700 LTR View Drop Down
Gold
Gold
Avatar

Joined: 02 Oct 2012
Status: Offline
Points: 834
Hi Guys, 

I have a FC390 with a 30hp 2stroke merc which is OK, but I want a new motor with more grunt. 

The only problem is the transom is rated to 50kg the engine I'm looking at is around 65-75kg 

Is there any way around this? 


Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote foulplay Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 10:06am
foulplay View Drop Down
Silver
Silver


Joined: 11 May 2014
Location: Auckland
Status: Offline
Points: 240
Jeepers. 30hp would be tops on a fc390. I own a 390 and have a 20hp fourstroke merc on it. I would check with fishcity about that max rating. My brother has the fc430 and upgraded outboard to a 4stroke yammie 40hp. It hauls at half throttle. Perfect match. So any more than 30hp would be touch and go i reckon on a 390
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote 700 LTR Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 10:20am
700 LTR View Drop Down
Gold
Gold
Avatar

Joined: 02 Oct 2012
Status: Offline
Points: 834
I just find it seriously sluggish with 3 POB when we head over to Rangitoto for a picnic chuck a bit of picnic stuff cooler with food etc and it hardly gets on the plane... 

and the 2 stroke is noisy etc  
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote 700 LTR Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 10:21am
700 LTR View Drop Down
Gold
Gold
Avatar

Joined: 02 Oct 2012
Status: Offline
Points: 834
I'm looking at either the 25 or 30 e-tec 
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote Redfinger Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 11:46am
Redfinger View Drop Down
Titanium
Titanium
Avatar

Joined: 29 Jul 2002
Status: Offline
Points: 7116
Is a 30hp etec two stroke going to give you that much more power than a 30hp two stroke merc - would doubt it?.
Yes there is a weight restriction of 51kg on transom.
If planning a heavier engine best thing to do would be to discuss with FC Boats directly (ask for Max) if you still want hull warranty conditions to apply.

If on normal useage with say two people your 30hp Merc should have plenty of power - they are noisy though , give you that.
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote 700 LTR Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 12:16pm
700 LTR View Drop Down
Gold
Gold
Avatar

Joined: 02 Oct 2012
Status: Offline
Points: 834
The hulls 2014 so i doubt its still under warranty? 
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote Redfinger Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 12:30pm
Redfinger View Drop Down
Titanium
Titanium
Avatar

Joined: 29 Jul 2002
Status: Offline
Points: 7116
oh ok - would have only just expired .
Up to you then what you want to do - the etecs are ok and technologically advanced - had one on my fyran a few years ago and was good (until oil pump went ). But chances of something going wrong a little higher too maybe because of that technology?
Im sure you done your homework so best of luck to you - if it was me I would stick with the simple but noisy merc 30
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote 700 LTR Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 12:47pm
700 LTR View Drop Down
Gold
Gold
Avatar

Joined: 02 Oct 2012
Status: Offline
Points: 834
Basically, I want something that will push the boat along with 3 POB when I need and something I can start when I leave the boat ramp and turn off when I get back if I'm drift fishing which is all of my fishing. 

The E-tec so far suits those requirements and has a 5-year warranty  
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote Keith C Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 2:30pm
Keith C View Drop Down
Platinum
Platinum
Avatar

Joined: 17 Jul 2002
Location: Urenui
Status: Offline
Points: 2961
Would pay to also check your insurance cover should you exceed the manufacturers maximum spec, irrespective of the warranty.
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote letsgetem Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 3:15pm
letsgetem View Drop Down
Titanium
Titanium
Avatar

Joined: 09 Oct 2008
Location: Whangaparaoa
Status: Offline
Points: 3171
Also - don't forget the maximum weight is for your benefit - if exceed that, might have problem - such as, being hard to get on the plane due to too heavy arse (when 3 POB).
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 6:51pm
Steps View Drop Down
Titanium
Titanium


Joined: 14 Oct 2013
Location: Franklin
Status: Offline
Points: 12849
Is a 30hp etec two stroke going to give you that much more power than a 30hp two stroke merc - would doubt it?.

 Well yes and no, storta
4S lack the same power a 2S has at lower rpms.. and for the marketing boys to get around this  with their marketing propaganda, in general 4S are around 10 to 15% more max hp than advertised Wink
 Hence why they also tend to be more economical...
Even so the 30hp 4S will only be about 35hp with a very similar low to cruise rpms power of a 2S.
 In the reakl world would that be significant enough to make the required difference.

 As to having an extra 50 kg in the stern..hull performance not structural stuff, drop a couple 25L containers in the back and find out..

Forgetting manufactures specs etc for now...
 With current motor.. what is the WoT  and cruise speed when boat is only loaded to the level these are acceptable?

And when fully loaded up struggling, what is the WoT and cruise speed then?

you may well find a change of prop for partly loaded and fully loaded .. sort of the same thing on boats a little larger  when used for sking , and then for general use.. sking with bigger load, they change to a lower pitch prop.. higher rpms at given speed means motor produces more power in that rpm range.

 Maybe a couple options to consider looking into that maybe the numbers add up ..

 
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote MacSkipper Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2019 at 7:07pm
MacSkipper View Drop Down
Titanium
Titanium
Avatar

Joined: 04 Jul 2014
Location: Manukau Harbour
Status: Offline
Points: 4478
I wondered about propping to - my experience is that not often done correctly just out of box alloy and she will be okay attitude.  Do you have a tacho on it does it rev out when fully loaded or lightly loaded for that matter...what condition is your prop in?  Is it stainless or alloy?  If damaged (alloy is soft) and wrong size anyway...a stiletto stainless prop will give you a bit more and it might be enough?
Good fishing trip nothing breaks, great trip catch fish.
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote out2sea Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 2019 at 12:31pm
out2sea View Drop Down
Silver
Silver


Joined: 01 Feb 2015
Location: Auckland
Status: Offline
Points: 211
I had a Frewza 4.1 that i brought new with a 30hp Merc two stroke on it and I was disappointed with it from day one. I did about 20 hours on it before I replaced it with a second hand 30hp e-tec. The biggest difference was the electric start and power tilt. It had noticeably more power all the way through the rev range and didn't struggle getting up on the plane with 3 people although it didn't add any more top end speed. (It had a permatrim on it when I brought it which may have helped with the planning). The e-tec was quieter but not as quiet as a four stroke.

The other option would be to go to a 3 cylinder 30hp Yamaha 2 stroke which from what I've heard from others was a better match for the Frewza 4.1 with a more top end speed and torque than the Merc. Although not sure if it would be within the stated weight limits.
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote Blindspot Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jan 2019 at 4:54pm
Blindspot View Drop Down
Platinum
Platinum


Joined: 19 Jan 2006
Location: Mangere Bridge
Status: Offline
Points: 1560
just fit it with a lower pitch prop (10-11") problem solved... you loose some top end speed but will give you a better hole shot.  We did this with a Yamaha and were easily able to get on the plane and stay there.  I would not worry too much about the top end RPM as most motors will happily do 4500-5500.
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jan 2019 at 5:58pm
Steps View Drop Down
Titanium
Titanium


Joined: 14 Oct 2013
Location: Franklin
Status: Offline
Points: 12849
I would not worry too much about the top end RPM as most motors will happily do 4500-5500.

 According to manufacturer.. and usually in bold letters, and to all their agencies and workshops.
 Not being in the recommended rpm range will put load on the power head right thjru the rpm range.
 And if one manages to source rpm/ power specs, its very true and confirmed by experienced mechanics..
 Any work done by workshops and any warranties are immediately void 

lower pitch prop (10-11") problem solved... you loose some top end speed 
 As I have said before.. top speed is constant.. basic high school physics.. thu in practice it may change marginally... but then different day, different water temp different air pressure, slightly different load will do the same...

 If I am wrong..and manufactures, workshops manuals etc then state exactly why.
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote Blindspot Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jan 2019 at 3:10pm
Blindspot View Drop Down
Platinum
Platinum


Joined: 19 Jan 2006
Location: Mangere Bridge
Status: Offline
Points: 1560
as per the Merc 30 spec

Full throttle RPM
4750-5500

so yeah with 750 RPM to play with its not hard to land somewhere in the recommended range with the props I suggested.

I'm not here to argue, chances are he will loose some top end speed due to slippage etc but a lower pitch prop will get you on the plane quicker - i have proven this testing 10-14" props on my Yamaha 30D.
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jan 2019 at 6:35pm
Steps View Drop Down
Titanium
Titanium


Joined: 14 Oct 2013
Location: Franklin
Status: Offline
Points: 12849
I'm not here to argue,

Im not stating 'Steps theory stuff' or opinion
What Imstating is what scientists, marine architects like Newton, found out and guys like Gerr, Crouch have then adapted to marine conditions.
 Its about as reliable as the apple that fell on Newtons head.

 I understand how you come to this conclusion..
chances are he will loose some top end speed due to slippage etc
 But it is a slightly incorrect observation.
 As I have said the WoT speed will be constant withing the Manufacturers RPM , as that range is at the top of the HP range..
The boat WoT speed will stay constant.. within the parameters I explained above...change the prop and the slip will change to maintain that speed... not the other way around...
The boat will reach that speed at a different rate with a change of prop, just as a drag car will change its 1/4 mile time...thu it may not reach its top speed within that 1/4 mile.

 I VERY VERY highly recommend reading gerr etc to get a simple basic  understanding and concept of actually how and what happens..
 It is not a guestimate or hit n miss or try this or that till it seems to work..
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote The Tamure Kid Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jan 2019 at 11:11pm
The Tamure Kid View Drop Down
Titanium
Titanium


Joined: 25 Aug 2015
Location: Auckland
Status: Offline
Points: 4817
Originally posted by Blindspot Blindspot wrote:

as per the Merc 30 spec

Full throttle RPM
4750-5500

so yeah with 750 RPM to play with its not hard to land somewhere in the recommended range with the props I suggested.

I'm not here to argue, chances are he will loose some top end speed due to slippage etc but a lower pitch prop will get you on the plane quicker - i have proven this testing 10-14" props on my Yamaha 30D.

This is an interesting discussion re props and the impact they have. I've got a four-stroke 40hp Merc, and i'm pretty happy with the performance (I'm a relatively new boatie, so having little to compare it to). Can you please help me with an explanation about why you prefer getting on to the plane faster than having higher top end speed?

Admittedly I seldom drive at flat out, usually at 4200-4500 RPM, even if it's flat enough to go full tilt. But on a typical trip, I don't go from zero to on the plane that often. I spend much more time at higher speed (to and from the fishing grounds) or puttering around (when at the fishing ground, setting drifts, looking for sign etc).





Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jan 2019 at 9:29am
Steps View Drop Down
Titanium
Titanium


Joined: 14 Oct 2013
Location: Franklin
Status: Offline
Points: 12849
Can you please help me with an explanation about why you prefer getting on to the plane faster than having higher top end speed?

 If you have been or had an under powered boat.. little or no reserve power at low and cruise....and takes ages to get up on the plane... climb up over the bow wave...the go on a min or well powered the difference is that of frustration to " all holding on? , lets go fishing"

That bow wave is the same wave that when in chop, in min or under powered, working the throttle, and falls off the plane..need more throttle to get back up over the bow wave, plus the chop wave.. then go over and the boat comes down with a big crash.

A min or well powered boat there will be around 2 to 3" difference in the pitch if the slip is correct.. which will be the same or withing 1/4" diameter of both props..
 In the real world.. the actual difference in the hole shot is so minual that it would be very hard id able to detect without a stop watch.
 The difference between just under or min powered and very well powered is about 4" in pitch.. little if any difference in diameter.. 1/2" tops.
 And rather than " all holding on? , lets go fishing"
 It is All holding on" skipper turns actually checks everyone IS holding on AND holding onto something substantial.. not bimini cover frame...

My understanding of Merc 30hp WoT rpm ranges are
30 HP 1994-2002 4500-5500
30 HP 1999-2005 5500-6000 
30 HP 2006   up    5250-6250 
Back to Top
Post Options Post Options   Likes (0) Likes(0)   Quote Blindspot Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jan 2019 at 1:45pm
Blindspot View Drop Down
Platinum
Platinum


Joined: 19 Jan 2006
Location: Mangere Bridge
Status: Offline
Points: 1560
In my case it came down to the heavy loading of the boat, we were using it for LBG and with 3ppl + gear on board, it was slow to get on the plane and we had to move weight forward... thats fine in good conditions but when the weather turns... it got really hairy and very unsafe.

lower pitch props give you more grunt/acceleration from standstill, 1-2" pitch change absolutely noticeable change in smaller outboards.  If you need to accelerate out of a sticky situation (i.e, a wave breaking on you) that low end acceleration is a must.
Back to Top
Forum Jump
Forum Permissions View Drop Down


This page was generated in 0.461 seconds.

Fishing Reports Visit Reports

Saltwater Fishing Reports
Top of the South Fishing Report - 22/03/24

Tasman and Golden Bay snapper still running hot We are not far away from daylight... Read More >

22 Mar 2024
Saltwater Fishing Reports
Bay of Islands Fishing Report - 22/03/24

Variety is the spice of life On one recent trip, the plan was to spend a... Read More >

22 Mar 2024
Saltwater Fishing Reports
Hauraki Gulf Fishing Report - 22/03/24

Fish where the fish are! Catching fish or just going fishing? I tackle this issue... Read More >

22 Mar 2024
Saltwater Fishing Reports
Inner Hauraki Gulf Fishing Report - 22/03/24

Thoughtful tactics required for better fish Over the course of each year the fishing varies,... Read More >

22 Mar 2024
Fishing bite times Fishing bite times

Major Bites

Minor Bites

Major Bites

Minor Bites