Prop replacement for 21' hull 3500 lbs. 300hp 5.7L volvo penta DP-C1 outdrive

Status
Not open for further replies.
Joined
Jun 20, 2014
Messages
10
Boat spec says the 1995 21 concept cuddy is 3475 lbs. dry and Nada guides say 3100 lbs.. The Volvo penta is model DP-C1 according to the metal tag. I'm having trouble finding information, but one source says the ratio on DP-C1 is either 1.95 or 2.3, so I would think 1.95. I found a number on the outer prop that looks like 844399 (could be B44399 or 344399). I just converted from 5.7Gi-PHUS TBI to 4bbl carb Rapido Marine reman., allegedly with 300 hp from flat pistons and an oversize cam. Anyway, just broke the engine in per Rapido's recommendations for 10 hours, did first oil change, and then took it out again last weekend and hit a rock that did some damage to the aluminum props. They weren't in the greatest of condition, but now they need to be either repaired or replaced, and I may replace and get the old ones repaired as spares.

I didn't get to WOT before they were chewed because the seas were a little choppy. I was hitting 30 mph or so against the current at about 3200 rpm before the prop damage which seemed fine, great pickup and got on plane quick, so I will probably want to replace with what was on there. I can't find information on 844399 model to determine size and pitch to order the replacement. Any guidance on this or whether I should deviate from what was on there? Again, not sure what that was and I guess I need to remove them to find the size and pitch label.
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
That number is not in the prop guide, and also not in a part number supercession list. There will be a part number as well as the series Being aluminum, the series is the letter "B" and then a number from 1-8. The part number is 6 digits, and some are close to what you posted but it does not match anything in the book exactly. When you get them off look in between the blades horizontally and you should be able to find the "B" series number and the part number. The main thing to find is the "B" series number as that identifies the pitch more or less. A B1 is lower pitch than B8. Most boats that size would have come with B7, maybe B6.

By way of comparison I have a similar size boat with 5.7 275hp and use B5's for towing. Very responsive and I can get to 48 mph. With the B7's it could go past 50 but was slow to get there and tended to drop off plane sooner when towing.

Your ratio is almost certainly the 1.95. I know 4.3's came with the 2.3.

Do a search here for Volvo prop guide, I have posted and attached that guide a few times. This latest version of the site won't let me but the older posts are still there.
 
Joined
Jun 20, 2014
Messages
10
Thank you so much for the info and link, Maclin! I read through my manual and absolutely it is 1.95. I think you have given me enough info to go searching for the replacement prop now.
 
Joined
Jun 20, 2014
Messages
10
So my drive uses either the b or c series. The size/weight/engine size/rpm range chart suggests either a c/b-6 or c/b-7 prop. The ideal wot range is 4600-5000 rpm from the 350ci 300hp engine powering the 21' hull 3400 lb. boat where out of the gate is not as important to me as top speed for longer trips. Any thoughts on a c6 versus c7 prop for this boat?
 
Joined
Jun 20, 2014
Messages
10
I ordered the Volvo removal tool #873058 today so I can get these off then find out what it has been running since I've owned it (about 10 months now).
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
I think because of this statement "...where out of the gate is not as important to me as top speed for longer trips..." I would go with the C7 or B7.
 
Last edited:

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
I meant to add this, Volvo recommends the C series stainless for speeds over 45 mph I believe, that is stated in the prop guide.
 
Joined
Jun 20, 2014
Messages
10
Thanks again, Maclin! I went ahead and bought a used set of C6. I had read that about the stainless recommendation over certain speeds and figured it was the way to go. If C7 was available, I would have gone with that, but figured a top speed difference of a few mph between C6 and C7 wasn't too bad. I got the rear prop off and it was a B5, so the C6 set should be a little closer to what I am looking for.
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
I was going to mention earlier that if you found a deal on some C6's to jump on it.. good job! C6's should do well for you.
 
Joined
Jun 20, 2014
Messages
10
No Title

Hmmm, a little hiccup in the plans. I ordered the C6 props, they arrived, I put them on but there is a sizable gap between the front and rear prop. The C6 rear prop is shorter than the former B5. The C6 rear won't extend far enough because the inside doesn't recess far enough back and/or the outer casing isn't long enough. I'm wondering if there is a spacer needed or available between these two, or why this condition exists. Any thoughts?
 

Attachments

  • photo220362.jpg
    photo220362.jpg
    14.4 KB · Views: 0
  • photo220363.jpg
    photo220363.jpg
    18.6 KB · Views: 0
  • photo220365.jpg
    photo220365.jpg
    20.1 KB · Views: 0
  • photo220366.jpg
    photo220366.jpg
    17.6 KB · Views: 0
Joined
Jun 20, 2014
Messages
10
The zinc anode I ordered is 1/8" or so shorter than the one that was on there, but that is not what the prop rests against. Looking at the manual and some videos, I may be missing (and was previously missing from the previous owner) some parts along the spline. I don't have any fish line cutters, and on one youtube video I saw a bearing cover over the front locking nut which I do not have. I also don't seem to have the rear thrust washer. If nothing else, I have some purchasing to do, but not sure if that is the problem with the gap between props or not.
 
Joined
Jun 20, 2014
Messages
10
O,k,, I'm working my way through this. I misplaced the thrust washer away from the other parts when I removed them. Two props fit together perfectly. HOWEVER...the front prop blades hit the little trim tab on the bottom of the lower drive. I'm not sure if they need to be adjusted or if they need to be replaced with a smaller model to fit the larger C6 prop, but they are hitting.
 
Joined
Jun 20, 2014
Messages
10
And the learning continues. So it is VP part 854054 and is referred to as a steering fin or trim tab. I read how to remove it and have PS, but I guess I just need to adjust it. It is a little bent up, so maybe I should get a new, smaller one or figure out how adjustable this is. I plan to explore this weekend. This place is a great resource for information.
 
Joined
Jun 20, 2014
Messages
10
A little update if anyone runs in to a similar situation as mine. New props work FANTASTIC!! I know the SS is recommended for higher speeds, and they felt good, whether it was the size change, materials change or both. Lost nothing out of the hole. As a matter of fact, it seemed to be more responsive and got on plane quicker. Maybe just my imagination. I ended up filing the steering tab a little with the grinder and straightening the fins where they were a little bent. Everything works great on it.
 
Status
Not open for further replies.
Top