Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-18-2020, 04:48 PM   #1
Member
 
City: Queen Charlotte, BC
Join Date: Jun 2020
Posts: 5
Propellor Sizing

Hello all...new member here from Haida Gwaii, British Columbia. I have a 1981 Monk 36 with a 24/20 wheel. Power is a Lehman 135 with a Newage 2.5:1 gear. I need to run it at 2000 rpm to get 7 knots, which seems a little lacking. Can anyone tell me other power/gear/wheel size combos and their speeds? Thanks.
__________________
Advertisement

mvermeer is offline   Reply With Quote
Old 06-18-2020, 05:25 PM   #2
Guru
 
High Wire's Avatar
 
City: Cape May, NJ and Englewood, FL
Vessel Name: Irish Lady
Vessel Model: Monk 36
Join Date: Dec 2007
Posts: 3,514
Welcome aboard!
Typically a Monk 36 has a Borg Warner 2.57:1 trans and either a 24Dx20P 3 blade prop or a 25DX20P prop with a Perkins. You have a Lehman which not many Monks have.

The question is what RPM do you hit WOT?
Have you verified the RPM with a photo tach?

Just curious what Hull # is your Monk. Its got to be #1 or 2.
__________________

__________________
Archie
Irish Lady
1984 Monk 36 Hull #46
Currently in Englewood Florida.
High Wire is online now   Reply With Quote
Old 06-18-2020, 05:29 PM   #3
Guru
 
Comodave's Avatar
 
City: Au Gres, MI
Vessel Name: Never Say Never
Vessel Model: President 41 DC
Join Date: Jul 2015
Posts: 9,526
Welcome aboard. Agree on verifying RPM with a photo tach and seeing if you can reach WOT RPM per specs. 2000 RPM at 7 knots doesnít seem too bad with a single but I have twins so I canít really compare it to my boat.
__________________
Boat Nut:
If you are one there is no explanation necessary.
If you arenít one, there is no explanation possible.
Comodave is offline   Reply With Quote
Old 06-18-2020, 05:32 PM   #4
Member
 
City: Queen Charlotte, BC
Join Date: Jun 2020
Posts: 5
Hello High wire, thanks for the reply. I’ll get back to you on WOT and hull number. RPM has been verified, yes.
mvermeer is offline   Reply With Quote
Old 06-18-2020, 05:38 PM   #5
Member
 
City: Queen Charlotte, BC
Join Date: Jun 2020
Posts: 5
Thanks Comodave. What’s got me thinking about this is people I know with similar boats and running gear only turning up to 1600-1800 and getting 8-9 kts.
mvermeer is offline   Reply With Quote
Old 06-18-2020, 06:52 PM   #6
Guru
 
High Wire's Avatar
 
City: Cape May, NJ and Englewood, FL
Vessel Name: Irish Lady
Vessel Model: Monk 36
Join Date: Dec 2007
Posts: 3,514
Quote:
Originally Posted by mvermeer View Post
Thanks Comodave. Whatís got me thinking about this is people I know with similar boats and running gear only turning up to 1600-1800 and getting 8-9 kts.
No Monk 36 or GB 36 is getting those numbers with a 135 hp engine. Cummins 210 maybe or with a 2 knot following current. I can only make about 8.5 knots WOT. My normal cruise is 6.7-6.9 knots at 1700 RPM. After that itís about 100 RPM per 0.1 kt extra. Just a waste of fuel.
__________________
Archie
Irish Lady
1984 Monk 36 Hull #46
Currently in Englewood Florida.
High Wire is online now   Reply With Quote
Old 06-18-2020, 07:37 PM   #7
Member
 
City: Queen Charlotte, BC
Join Date: Jun 2020
Posts: 5
WOT is 2500RPM. To be honest, I had no idea what you meant by WOT lol! Sorry....I come from a commercial background...new to the leisure world.
mvermeer is offline   Reply With Quote
Old 06-18-2020, 08:04 PM   #8
Member
 
Join Date: Mar 2012
Posts: 16
You have to see what the engine will turn at wide open throttle. To make sue that your wheel isnít too large for the boat. If the engine canít reach itís rated rpm it isnít good for the motor. Itís really difficult to try to compare with other peopleís boat without knowing the weight of the boats to compare. Growth on the hull or the prop will kill the performance.
dsharp is offline   Reply With Quote
Old 06-18-2020, 08:43 PM   #9
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 17,199
Welcome mvermeer,
So glad you’re a member now. I think you’re the only one from QCI.
I was there for 7 months or so teaching shop at Masset in about 72. On a trip to Alaska we stopped at Rupert and took the ferry across to QCC. Rented a car for several days and spent some time between Tlell and Tow Hill including the trail from Tow Hill to Hecate Strait.

You’re in good hands here regarding WOT. I prefer to do WOT at 50 to 100rpm over rated rpm. Still using about 18hp to cruise the Willard at a tad over 6 knots.
If you’re so inclined we’d all love to see pics of your boat. Five years or so there were more Monk boats active on the forum.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 06-19-2020, 12:06 AM   #10
Guru
 
City: Qualicum Beach, Vancouver Island
Vessel Name: Capricorn
Vessel Model: Mariner 28 - Sedan Cruiser 1969
Join Date: Feb 2019
Posts: 1,341
Well you are in an area of great cruising locations. I can't help you with your prop problem but I thought I'd post a welcome here.
rsn48 is offline   Reply With Quote
Old 06-19-2020, 05:22 PM   #11
Member
 
City: Queen Charlotte, BC
Join Date: Jun 2020
Posts: 5
Thank you! Glad to be here. I have the boat up on the hard now, will do some sea trials once back in the water and get some numbers. Once I figure it out, Iíll post some pics.
__________________

mvermeer is offline   Reply With Quote
Reply

Tags
wheel size

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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



» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 04:59 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×