1984 offshore questions

[Tclark828]

Hi guys, new to the forum here, did some browsing and it seems like there is a lot of useful information on here. I purchased my first boat at the end of last season, a 1984 24' Offshore with an OMC Sea Drive. The engine was repoweredby the original owner a few years ago and runs strong.

Now for the questions, lol. At times the boat seems extremely sluggish, the trim tabs dont work, and im wondering if this is the entire problem. Ive only been in the bay so far so cant comment on how it handles the ocean. Im also wondering at what rpm i should be cruising at. I generally keep it at 3500, there isnt a yellow or red line on the tach, so im trying not to overwork the engine. Sometimes it will up to 18kts at 3500, and sometimes it only does 10. The times its going 10 seem to happen for no rhyme or reason, its not like i am driving into a stiff breeze or anything like that.

Is there major modifications needed to upgrade the engine? It has the full transom, but not sure if it would have to be beefed up or modified to put a regular outboard on there. The boat is a gas hog, so it seems like an upgrade would pay off in the long run. Any suggestions in this area would be greatly appreciated!!

Im also having trouble finding parts for the boat, such as cushions etc. I would also love to find a hardtop for it, does anyone have a place to look for that? Thanks in advance for any help.

 

[JeffN]

T you have an old boat there. I am not being critical as my boat is older than yours but I would suggest keeping things in perspective for a while. At least until you have a good feeling for the boat and decide if you are in it for the long haul or not. It will not take many upgrades before you have more in the boat than it is worth. I think I would begin by fixing the trim tabs. That should not be too expensive and you can decide if you like how the boat handles etc. once they are functioning. They make a big difference. Somewhere on your motor there should be info concerning the RPM that motor should run at WOT. Once you find that you can see if the motor is propped correctly. You say that the engine runs strong, is the problem you are having running at 3500 RPM and going at 10 knots or 18 seem to be related to sometimes the boat is on plane and others it is not? Tabs would effect that for sure. Tabs down and engine trimmed in will help you get up on plane faster. I am not very well versed in OB/Sea Drives but 3500 seems a bit low. I'm thinking you can run higher than that at least to get up on plane and then see what RPM you need to keep it there. One of the OB guys can fill you in on that score. Probably as you already have a full transom a bracket would be the way to go when and if you decide you are going to keep the boat a while a want to repower. As sea drives are long out of production be careful about dumping money into the motor. In regard to cushions just find someone in your area that does that sort of work and have them make you a set. Just my take on your questions.

84Offshore who is here on the board has your same boat but with an I/O. I'm sure he can offer you some good advice on questions about handling etc.

 

[cgmiller]

T.....the age of your boat should not be a factor with performance. I dont think you said what HP your seadrive was? I ran a 80's 24 down in the Keys with a 200 Merc and it humped along...3500 rpms is probably the bottom end of efficient cruising...3500-4000 is a good rpm range for an outboard. You do need to check out your WOT..if you are not making the recommended wot becuase your prop is too big, it will be overworking your engine leading to higher than normal fuel burn. Are your tabs stuck down or level? if they are down, that will cause the front of the boat to plow...if your engine is tilted down to far (or in), that will also cause your bow to plow and slow you down. You should not see an 8 knot decrease in speed at the same rpms due to current and waves..maybe 2 or 3 knots, but not 8...unless you are running downsea with a large swell than that will slow you down...I had a 24 Rampage with an IO and I would go from 17 knots to 14 knots w/o touching the throttle or trim due to waves and current....

 

[rcgtsport]

you could go to grady white web site under costomer resources you can download owners manual. i to bought 84 offshore 5.7 for first boat still workin on getting it in water. good luck, hope it helps. i got a service manual for mine off ebay

 

[ocdansar]

I owned a 1984 offshore for 13 years, I sold the boat in 01, it had a hardtop and when I bought it it had a single 200 mercury it was very sluggish and hard to handle in a following sea. I repowered it after a year with a pair of 150 mercury's I added the aux fuel tank and hydraulic steering, It was a huge diffrence and like a totaly diffrent boat, that was the best money I ever spent on that boat. my family really enjoyed that boat.

 

[Tclark828]

Thanks for all of the info guys, i really appreciate it. I am going to look at getting the trim repaired and see if this makes a big difference and then go from there.

 

['84Offshore]

You still haven't told us what the engine is...........

 

[Tclark828]

You still haven't told us what the engine is...........

Its the 2.6L Sea Drive engine, i believe its 200 or 225 hp

 

['84Offshore]

@ 200HP I would say it would be underpowered.
How are you measuring your speed and how accurate is your tach?

 

[Tclark828]

Thanks for all of the replies, havent gotten on here in awhile, been super busy. Im just using my GPS to measure speed, and Am just assuming the tach is correct. I found that the WOT of that motor is 5500 rpms. Ive been running it at 4000-4100 and it is running much smoother at around 20kts. The boat is absolutely horrible on gas and am wondering if its worth getting repowered or if i should just look to upgrade to something newer.

The motor runs fine, but the bost is beyond bad on gas. I am tryi g to find out if its worth upgrading to a new engine or just selling and looking for a new boat. I would need a good used, armstrong bracket, and the back would have to be re-enforced to handle the weight. Just from looking arounf a decent used motor will be 5k, the bracket is 1500+, plus all of the other work and whateve misc parts needed. Seems like 10k is a safe ball park estimate. I bought the boat for 5k, and am pretty unsure of what to do next. At the end of the day it is still 30 years old. Any info and advice is greatly appreciated. Thanks!!

 

[JeffN]

Did you get the tabs fixed and functioning?