Reply
 
Thread Tools Search this Thread
 
Old 03 September 2011, 10:49   #1
Member
 
Country: UK - England
Length: 3m +
Join Date: Jul 2011
Posts: 32
Tohatsu 30hp 2s low speed help

I'm currently running a tohatsu 30hp 2 stroke 2003 on a 4metre honwave but my top speed is only 25mph, I expected a little more than this, what could be wrong engine only has 20hrs from new and is running a 9.6x13 prop.
__________________

__________________
stevessub is offline   Reply With Quote
Old 03 September 2011, 15:14   #2
Member
 
Country: UK - England
Town: Looe
Make: Delta
Length: 4m +
Engine: Mercury
Join Date: Apr 2004
Posts: 1,335
25mph does'nt sound to bad to me!
__________________

__________________
Black Dog Marine
www.blackdogmarine.com
Turbodiesel is offline   Reply With Quote
Old 03 September 2011, 15:38   #3
Member
 
Country: UK - England
Town: Lancashire
Length: 5m +
Join Date: Jun 2011
Posts: 87
Have you tried putting the trim pin up a couple of notches? It seemed to make a noticeable difference to mine. Also i take it this is your video i was having a laugh at the other day?

__________________
LWman is offline   Reply With Quote
Old 03 September 2011, 17:46   #4
Member
 
TomKat's Avatar
 
Country: Ireland
Town: Bangor
Boat name: Lencraft 4.8m
Make: Lencraft
Length: 4m +
Engine: DT55HP Suzuki
Join Date: Jul 2011
Posts: 469
check the throttle is opening fully, I have a 30hp Mariner which I understand to be a Tohatsu. I have spent the last few evenings getting the throttle 100% open, tried it out today and easily get 35 knots (with just me in the boat!). The cable/rod did not have enough stroke to fully open the throttle so I bodged a fix and seems to work OK.
__________________
TomKat is offline   Reply With Quote
Old 03 September 2011, 18:30   #5
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,112
It doesn't sound like its majorly off from what you might expect (I'd have thought you'd get a bit more in that I can get just manage 25 mph lightly loaded with a 20HP on a 4m boat). I'd be surprised if you get much over 30 mph easily. What speed were you expecting?

You might be able get better than you are doing by playing with props, trim, boat load and inflation pressures etc. Starting point for logical improvements is probably to know what RPM you are achieving though.
__________________
Poly is offline   Reply With Quote
Old 04 September 2011, 02:12   #6
Member
 
Country: Finland
Town: Helsinki
Boat name: SR 5.4
Make: Avon
Length: 4m +
Engine: Toh1 3,5 Yam 90/2S
Join Date: Oct 2009
Posts: 896
The rig on this model is slightly longer than on most other engines, at least this was the case on the long rig model. Check the cavitation plate hight compared to lowest point on transom, maybe you need to lift the engine slightly?
__________________
fun on a boat is inversely proportional to size...sort of anyway
C-NUMB is offline   Reply With Quote
Old 04 September 2011, 05:12   #7
Member
 
Country: UK - England
Length: 3m +
Join Date: Jul 2011
Posts: 32
tried lifting the engine up a few notches and found the 3rd one from bottom is the best (25mph) Im starting to think it could be the prop, If i go for a 9.9x14.2 would i gain much. the prop i have at the moment is 9.6x13, and its its second.
__________________
stevessub is offline   Reply With Quote
Old 04 September 2011, 05:21   #8
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,112
steve, I think C-NUMB is referring to the length rather than the angle. i.e. you could try moving the whole engine up the transom by an inch or so.

As for increasing the prop pitch this might actually make things worse. Without a tacho on there we are all just assuming you are achieving maximum revs. However if you are, the prop is slipping a lot more than I would expect. Before spending a 100 on a new prop I'd be spending 50 on a tiny tach.
__________________
Poly is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 12:26.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.