Besides prop, what all effects boat speed?

[Dgoods4u]

88 Bayliner Capri w/85 Force - I just got this boat from my grandfather and it came with an aftermarket 4 blade propeller and a whale tail. I have the original aluminum 3 blade propeller for it. I took it out and couldn't get it over 25 mph via GPS as the speedo isn't working. Bayliner suggests top speed for this boat is 34. How much of a difference can an propeller/whale tail make? I should also communicate that the boat will not start (have to use carb cleaner) but runs strong whenever there's throttle. In addition, it hates to idle (will die unless I trim it up a little). Any takers?

 

[Scott Danforth]

welcome aboard

My guess is you mean propeller

first, stop using anything to start the motor and fix your carbs

its not idling because you need to fix your carbs

failure to fix your carbs will take out your motor as you are most likely running lean.

the whale tail will lower your speed

being a 1988 Bayliner, you should weigh it. most likely you are carrying around about 800# of water in the foam.

 

[Dgoods4u]

Yes, I meant propeller, thank you. I have figured out that the carbs need to be rebuilt. I'm curious about the propeller and whale tail. Some sources suggest that the whale tail offers more top end speed.

 

[Scott Danforth]

step 1 - fix your carbs
step 2 weigh the boat
step 3 do all the other maintenance

worry about step 4 after step 1,2, and 3

 

[wahlejim]

IF that is the case, any top end speed will be negligible and will only occur in certain circumstances (ie trimming properly at WOT it might offer a little more bow lift), but that is not your problem here. As Scott mentioned, you have some motor issues. Without achieving proper WOT RPMs, there is no point in dialing in a prop. But you may have a bigger problem here, Scott also mentioned them.

You have a 30+ year old boat and outboard combo that was designed and built to get people on the water as cheaply as possible. There was a lot of corners cut in the construction of these things. Even the best kept and maintained Bayliners from the 80s have run into water intrusion problems by now. Weigh the boat as empty as possible (take to a truck scale and drop the trailer right on the scale). You will probably find it is significantly overweight and carrying a lot of water. Then decide how you want to proceed.

 

[Dgoods4u]

Wow, that is really interesting. So you mean to tell me that the boat could be holding water somewhere outside of natural drainage areas? That never once crossed my mind. Thank you for sharing. I will take it to a weigh station and start there. Actually, isn't that what a bilge pump is for? Couldn't I run the bilge first to see if it's holding water? Sorry, I'm BRAND NEW to boating.

 

[Scott Danforth]

bayliners of that era were designed to be used between 10-15 years and replaced. the construction quality was shoddy at best

Unless your grandfathers boat was religiously pulled from the water after every use, the plug drain pulled, the boat wiped with a towel and stored in a garage, there is most likely water in the flotation foam.

on a capri 16' that has been historically several hundred pounds.

 

[Dgoods4u]

Where exactly is the flotation foam? My guess is that there would have to be a ton of water in there to equal a 10 mph deficit. If I determine the boat is severely overweight, what type of work would need to be done to correct the issue?

 

[Bondo]

Where exactly is the flotation foam?

Ayuh,..... Welcome Aboard,..... The foam is under the deck, above the hull, in the bilge,.....

If the foam is saturated, ya rip out the deck, remove the foam, glass in new wood where the old wood rotted away, 'n put the deck back in, also new of course,....

 

[Dgoods4u]

Gotcha, thank you for your response. It sounds like it would take the boat being in the water for long periods of time with water coming in to actually absorb all of that into the foam. The fact that it struggles to start and idle suggests to me that a carb may not be working right and therefore one piston not firing like it should. I'm going to get the boat on the water this weekend and spray oil and gas mixture in the mouth of each carb to see if the boat's performance changes. If it doesn't, it's off to weigh station. It would make sense for a boat this old to need three carb rebuilds and I've also heard they have electrical issues, too...process of elimination as I don't want to buy a new boat...this one is plenty fun. I really appreciate everyone chiming in.

 

[QBhoy]

The whale tail, doel fins or anything you bolt on, will certainly not improve any top speed from a well propped motor in the first instance. It’s impossible.
Fix your carbs first my friend, then ditch anything that’s been bolted on...and get a well suited 3 blade back on it. You will see your mid to late 30’s...all being well.

 

[Bondo]

It would make sense for a boat this old to need three carb rebuilds

Ayuh,...... Rebuildin' carbs is to get rid of the junk in there, from stuff other than gas that gets into the carbs,....

The older the boat, the more likely the need to rebuild the carbs,.....
'n I suggest ya do it before ya go boatin' again,.....

It sounds like the carbs are runnin' lean, 'n a lean condition is the quickest way to burn a hole in a piston,.....

 

[jimmbo]

What's the WOT range for your engine? 4750 - 5250? It needs to be running in that range at WOT, preferably in the upper half of it. A four blade, if the proper reduction in pitch isn't chosen can really kill performance, I will rephrase that, 4 blade props consistently reduce top speed, whether or not they allow the engine to run the WOT range

 

[wahlejim]

I would suggest weighing the boat FIRST. Rule out the worst case scenario. Take a look at the restoration forum for what is in store if you choose to replace wood and foam.

This is above and beyond the bilge pump. The foam is like a sponge. Drop a couple sponges in a 5 gallon pale of water and pump the water out. The sponges will still be soaked with water. Drop some plywood in that same bucket and tell me how long that plywood lasts. That is what happens to these boats over 30 years.

Weigh the boat and confirm the rot with exploratory holes. 1/4" drill bit right into the stringers and transom. If dry shavings come out, fill it with 5200 and you are good to go. If anything but dry shavings come out, time for a rebuild or sell the motor and trailer with a free boat attached.

Unless you have unlimited time and budget, I would think that a spring 2021 launch is feasible for a restoration. If you are motivated and have a lot of free time and about $4,000 for supplies, next year is not out of the question. The big kink in all of this, is even if you do a full restoration, the boat still won't be worth $4,000. Boat markets are weird.

 

[Dgoods4u]

I'm in the process of rebuilding the carbs and I have question regarding the correct part numbers. Is it normal for the carbs to be different from top to bottom? When I go to a parts catalog for my exact engine (year, serial #, etc...) it shows a different part number on the carb(s) then what I have.

 

[QBhoy]

If you have any doubts at all and maybe have a few hundred $$$ to spare. Without being cheeky...the best advice I could maybe give...is to sell the force and just get a good merc or Yamaha 90/80 hp. Will give you peace of mind reliability and add value to your boat.

 

[wahlejim]

I'm in the process of rebuilding the carbs and I have question regarding the correct part numbers. Is it normal for the carbs to be different from top to bottom? When I go to a parts catalog for my exact engine (year, serial #, etc...) it shows a different part number on the carb(s) then what I have.

You have a 31 year old Force motor. At the time, Force was built by Chrysler and has since changed hands and been eliminated. Chances are the carbs have been tackled before, hence the different numbers. It can be difficult to track down the proper parts for these outboards. You may have better luck in the engine repair section dedicated to Force outboards. Beyond that, I would personally go with the previous suggestion of finding a different brand to slap on there, you are probably rebuilding your transom anyway at this stage.

 

[legalfee]

The top and center / bottom carbs have different part numbers. The repair kits should be the same. I have a 1995 90hp Force and it runs like a champ. I would eventually like to get a Yamaha 4 stroke but there's nothing wrong with the Mercury Forces.

 

[Dgoods4u]

Ok, thank you for the response. I have all three off and awaiting new rebuild kits. I think it is really strange that they have different part numbers from top to bottom. Someday I might swap motors but for now I'm enjoying working on this thing, it's a great learning experience.

 

[legalfee]

Whats the serial number of your motor? You should have one part number for the top carb and another for the middle and bottom. I agree with the other posters in that I would check for rotten wood and foam before I'd worry about the motor.